How did the chain outdo Burger King’s Bacon Sundae, Pizza Hut’s hot-dog-stuffed crust, Cinnabon’s Pizzabon, and KFC’s fried-chicken-flavored nail polish?
An animation of a diagrammatic taco spinning on its central axis with small glowing diagrams around it that hint at the...
According to the company’s all-important Distinctiveness Rule, you can change either the taste or the form of a beloved food item, but not both.Illustration by Julian Glander

Lois Carson always wanted to find a new way to fold a tortilla. “Life’s like an experiment to me,” she said. For twenty-three years, when she worked for Taco Bell as a product developer, she thought and thought about how a tortilla might be wrapped around taco fillings in the shape of a hexagon. She wanted people to be able to pick up the stuffed tortilla with one hand, even while driving, without it falling apart. “It was just something that came into my mind,” she said, seated in a booth at a Taco Bell in Orange County, California. Carson is seventy-three and wears glasses, pink lipstick, and a Timex watch. She started her career in the nineteen-seventies, working in the kitchen at Perino’s, an Italian restaurant in Hollywood frequented by movie stars, where she devised methods to reconstitute the company’s frozen entrées for the microwave age. During her time at Taco Bell, she filled her lab book with sketches annotated with notes on the “build” of the potential hexagonal tortilla product, entering measurements of ingredients into a food-cost model. She practiced the fold technique studiously. “It’s like Thomas Edison and the light bulb,” she said. “He came up with an idea how many times? He made so many tries.”

Carson realized that if a hard-shell tostada were placed inside a tortilla it could provide interior scaffolding. Across the table from me, she put her iPhone on a sheet of paper and carefully folded the paper around it, to demonstrate. After she proposed the idea to her Taco Bell colleagues, in 1995, she went to the company gym to work out. “I explained it to this gal on the treadmill next to me,” she said. “She was in food operations, and she said there were all these technical reasons it wouldn’t work.” For one thing, Carson hadn’t cracked how to keep the folded hexagon from popping open. She went on to pitch the company’s executives repeatedly on her idea—which would eventually become the Crunchwrap Supreme, the fastest-selling item in Taco Bell history—but, noting the extra seconds required for a worker to make the folds, they initially dismissed the concept. “There’s all these parameters around your creativity,” Carson said. “You just have to wipe your mind of certain facts.”

Taco Bell’s food-innovation staff, which includes sixty developers, focusses on big questions: How do you make a Cheez-It snack cracker big enough to be a tostada? What are the ideal Cheez-It dimensions to guarantee that the tostada won’t crack inconveniently when bitten into? Or consider the Doritos Locos Taco: What safeguards can be implemented to prevent the orange Doritos dust from staining a consumer’s hands or clothing? Can fourteen Flamin’ Hot Fritos corn chips be added to the middle of a burrito and retain their crunch? Can a taco shell be made out of a waffle, or a folded slab of chicken Milanese? These are all problems of architecture and scalability; fast food is assembly, not cooking.

I recently visited Taco Bell’s headquarters, in Irvine, in a corporate complex off the I-5 freeway, next to Ford’s regional offices and a Marriott, to see how the company creates new menu items in its laboratory-like Innovation Kitchen. William Bradford, a musician who writes Taco Bell jingles under the name Yo Quiero Taco Ballads (he appears with Dolly Parton in a TikTok musical about the brand’s Mexican Pizza), described a recent visit to the test kitchen as “like being selected by Willy Wonka to go to the chocolate factory.” But the space, in ambience, is more WeWork than Wonka. When I arrived, flanked by communications professionals, the innovation team was huddled around a Formica table sampling a limited-edition collaboration with the dessert chain Milk Bar: a cake truffle with a saline taco-shell coating.

After passing through several doors that were unlocked via a coded keypad, I sat with Rene Pisciotti, the executive chef, who is known as the Taco Whisperer; Liz Matthews, the global chief food-innovation officer; and Heather Mottershaw, the vice-president of pipeline innovation and product development. (She invented the Waffle Taco.) I was handed a plastic cup of Baja Blast soda—tropical Mountain Dew in a proprietary shade of turquoise—and a plate of hard-shell tacos. Pisciotti, a burly man with gelled hair who used to work for Barilla, the Italian food company, averted his eyes in a practiced way as I took a bite, sending an avalanche of shredded lettuce and cheese onto the floor. He then summoned several assistants, who streamed in to hand each of us a sample of a new product: a burrito with melted cheese on top. He wanted to show me an example of how his team solved a problem.

“It’s a challenge, from an innovation standpoint,” Pisciotti said, of toasting cheese on top of a burrito at the end of the assembly process. The cheese goo acts as adhesive for four jalapeño slices studding the burrito’s exterior. “It has to be super quick on the line, but it feels cared for, it feels prepared,” Matthews said. “It’s a big unlock for us about how to actually have a totally different burrito-eating experience.” Mottershaw said that it had taken a year to perfect a material called “magic paper,” which covers the burrito when it’s in the grill press but does not stick to the melting cheese and does not burn. This was important, she said, to make sure “we don’t lose cooks in the restaurant.”

Matthews, who has long dark hair and was wearing a blazer, went on, “We knew it was an amazing idea, because it’s such a sensorial product.” A dairy scientist named Mike Ciresi had worked on the melted-cheese burrito every day for months. Part of Ciresi’s broader mission, as an employee of a trade organization called Dairy Management Inc., is conceptualizing how to get more dairy on the Taco Bell menu—“taking dairy from a garnish to the hero,” as he put it. The latest dairy-heavy hit is the Baja Blast Colada Freeze (two hundred and fifty calories), made with heavy cream. (D.M.I. was also behind Pizza Hut’s cheese-stuffed crust.)

“We’re patient—we play the long game,” Matthews said. “It’s all about this restless creativity.” She put down her burrito. “The first thing I ever came up with, eighteen years ago, was the Quesadilla,” she said. (The lowercase quesadilla, of course, was likely invented in Oaxaca hundreds of years ago.) “It was a huge success, and I was, like, Oh, crap, now I’m going to get fired. I’ve peaked.”

Mottershaw, who is British and has been with Taco Bell since 2003, said, “We start with big ideas, then we think about speed.” The team has to make sure that the recipe components can be prepared in vast quantities, and that the items can be cooked on the line in a minute or less. Then comes the all-important naming process. The cheese-topped burrito became the Grilled Cheese Burrito. “The name brings out emotion and nostalgia,” Matthews said. In the Innovation Kitchen, the words “nostalgia,” “emotion,” and “memory” are in heavy rotation.

In 1999, at the Mirage hotel, in Las Vegas, Mikhail Gorbachev gave the keynote speech at a fast-food convention sponsored by the International Foodservice Manufacturers Association. Gorbachev had written the foreword to “To Russia with Fries,” a memoir by a McDonald’s executive named George Cohon. (“And the merry clowns, the Big Mac signs, the colourful, unique decorations and ideal cleanliness . . . all of this complements the hamburgers whose great popularity is well deserved,” Gorbachev wrote.) The day’s presentations described enemies of fast food as enemies of progress.

“Not all of us think we should collect student debts personally.”

The innovation team at Taco Bell shares this zeal. Its work is intricate, the lab as much think tank as mad-scientist lair. Frito-Lay, which supplies the chain with taco shells, runs a research complex outside of Dallas that’s staffed by hundreds of chemists, psychologists, and technicians, who perform millions of dollars’ worth of research a year examining the crunch, mouthfeel, and aroma of each of its snack products. A forty-thousand-dollar steel device that mimics a chewing mouth tests such factors as the perfect breaking point of a chip. (People apparently like a chip that snaps with about four pounds of pressure per square inch.)

Some years ago, a headline in the Onion summed up the Innovation Kitchen’s challenge: “Taco Bell’s Five Ingredients Combined in Totally New Way.” The components themselves arrive at the chain’s seven thousand locations frozen or dehydrated. (In the late eighties, Lois Carson helped the company transition to using central manufacturing plants; the operation was called K-Minus.) Avocado paste, for guacamole, is made in giant vats at a factory in Morelia, Mexico, and is then frozen and shipped north in tubs. Ground beef arrives spiced and cooked, in vacuum-sealed bags. Beans come dehydrated, and resemble brown cornflakes. The tastes and textures have been formulated and manufactured long before, by Taco Bell scientists, who consider a food’s rheological properties, which include bounce, density, crunchiness, gumminess, springback, juiciness, and spreadability.

As menu items are developed, various iterations are tested at the Taco Bell Sensory Panel, at the company’s headquarters. Professional testers, trained by Taco Bell, along with members of the company’s broader workforce, sit in carrels at a long counter while researchers on the other side of a window slide trays of samples to them. Each tester has a silver button to push when ready for another dish. Pisciotti studies their faces in real time on a monitor and scribbles notes. “I have a camera on people—it’s not creepy, I promise,” he said. Sometimes testers pick an item up and immediately drop it. “And I’m, like, O.K., we have a temperature problem here,” he said. “We don’t want to hurt consumers.” Other times, “people just have a ho-hum look on their face.” The best scenario is when a tester eats an entire portion before saying anything.

There are twelve chef scientists on the innovation team, which is composed mainly of engineers and quality-assurance specialists. When I visited, researchers in lab coats were measuring ingredients (chopped tomatoes, ribbons of lettuce) on a scale, to insure that metrics remained consistent—each shred of cheese has to be a specific number of centimetres long.

Failure is a big part of the job. “There’s more items that don’t make it than ones that do,” Mottershaw said. “And there are things that are before their time.” Hypotheses are tested; experiments rarely pan out. The Crispy Melt Taco, introduced in 2021, “started out blue, because we made it with blue corn,” she said. “We called it Midnight Melt and Forbidden Taco, to try to give it a reason for having a blue shell. But people were confused—like, Is it made for nighttime? Is this old? What’s forbidden? What happened to it?” Pisciotti said, “The masses don’t know that blue corn is a thing—they don’t shop at Trader Joe’s.” (Other items that haven’t made the grade: the Croissant Taco, Crispy Cheese Curd Loaded Fries, Seafood Salad.) “We introduce things to the masses,” he added.

“People tell us everything they feel,” Matthews said. “We’re Madonna. We’re always reinventing ourselves.”

Taco Bell serves forty-two million people a week. Customers go through eight billion sauce packets a year—more than the number of people on earth. Innovation was always part of the company’s ambition. In the fifties, San Bernardino, east of Los Angeles, was known for its citrus orchards, its Air Force base, and its hamburger stands. Taco Bell’s founder, Glen Bell, opened Bell’s Drive-In there during those years. His biography, “Taco Titan,” by Debra Lee Baldwin, quotes him saying, “I was determined to beat the competition, so I decided to experiment.” Bell had ridden boxcars with drifters and then joined the Navy; in a general’s dining room on the U.S.S. Rochambeau, he had served rehydrated eggs to officers. After the war, he returned to San Bernardino, where the McDonald brothers had recently converted their orange-juice stand to a carhop drive-in. Bell bought tortillas from a nearby factory and fiddled around with different sauces, spices, and cooking techniques. He assumed that the idea was a lost cause when his first customer, a businessman in a pinstripe suit, dripped grease down his sleeve and onto his tie. Bell showed people how to tilt their heads in order to eat a taco. “We changed the eating habits of an entire nation,” he wrote.

At the time, no fast-food venders sold hard-shell tacos. (A Mexican restaurant near Bell’s stand sold a soft taco held together with toothpicks.) Bell had a vision of crisp concave taco shells ready to be filled, but first he had to modify a fry basket to hold tortillas. He asked a chicken-coop salesman to make him one out of chicken wire. It could hold six folded tortillas at a time. Next, he had to find a way to keep the cooked shells upright in his taco assembly line. The solution was a V-shaped metal trough called a taco slide. Each taco was supposed to weigh exactly three ounces. (In 1978, Taco Bell was purchased by PepsiCo, which owns Frito-Lay, and by the nineties a Frito-Lay factory in Mexicali was stamping out enough tortillas to yield four hundred cooked shells per minute.)

In 1962, Bell opened the original Taco Bell, in Downey, California. Bell’s first franchisee, a former Los Angeles police officer, would cook twenty pounds of beans in a pressure cooker and then mash them with a beater attached to a quarter-horsepower drill. By the mid-seventies, when the chain had more than three hundred outlets, only one menu item had been added to Bell’s original five (tacos, tostadas, burritos, frijoles, and chili burgers): an enchilada-burrito hybrid called the Enchirito. It was discontinued in the nineties, and sparked a “Bring back Taco Bell’s Enchirito!” movement. The menu soon expanded to include nachos, taco salad, and Mexican pizza. As drive-through lines grew, in the nineties, fast-food chains designed more car-friendly items, with the dashboard in mind as a table. It was around this time that Lois Carson started dreaming of the folded tortilla.

“In America, our food habits are still shaped by our Puritan values and work ethic,” Greg Creed, a former Taco Bell C.E.O., wrote in a 2021 book called “R.E.D. Marketing.” (R.E.D. stands for “relevance, ease, and distinctiveness.”) “That’s a big part of why fast food was born in the U.S.: we like and need portable food because it’s traditionally been seen as fuel, rather than an experience.” In the twenty-first century, the paradigm shifted. “Food is now absolutely an experience,” Creed wrote. “However it is still an experience shaped by our need for functionality and portability.” In the book, he endorses a popular theory—that, as American drivers switched to automatic transmissions, the nation collectively gained weight because it became easy to hold a snack in the hand that was formerly reserved for the gearshift.

The first notable update of Bell’s crunchy-shell taco was the Doritos Locos Taco, in which the taco shell is a supersized Nacho Cheese Dorito. The idea originated in 2009, during a brainstorming summit between Taco Bell and Frito-Lay leadership at the latter’s research lab in Texas. (A conflicting origin story: a man named Todd Mills, a former security escort for Bill Clinton in Arkansas, believed that he came up with it. He loved to make taco salad with Doritos, and he sent Frito-Lay a letter in 2009 saying, “Imagine this . . . taco shells made from Doritos.”)

Denise Lefebvre, a food-research executive at PepsiCo, told me, “We first tried triangle taco shells of different sizes, but those couldn’t fit enough filling.” To get the right taste and texture for the shell, Frito-Lay tested more than fifty recipes. The company had to come up with “a bespoke means to season taco shells,” Lefebvre said. “This took months to achieve, with lots of consumer input.” An early try involved using a Home Depot paint-spray gun to apply the nacho-cheese powder to the shells. Three inventors are credited on a patent titled “System and process for applying seasoning to a food item.” (Besides getting the coating on the taco shells, the process protected workers from being harmed by breathing in Doritos dust.) Along the way, the company also developed a cardboard taco holster to keep the orange dust from getting all over fingers and clothes.

The Doritos Locos Taco, or D.L.T., is designed to target taste buds using “dynamic contrast”—in this case, the sensation of biting through the crispy shell to the fat-laced filling. Exactly half of a D.L.T.’s hundred and seventy calories are from fat, the ideal ratio for a pleasing mouthfeel. The lactic acid and citric acid in the Doritos dust get saliva flowing and excite the brain’s pleasure center, signalling you to eat more. The taco has what industry scientists call a “long hang time” flavoring system, meaning that the lingering smell stimulates food memories and cravings; meanwhile, the multifaceted flavors are strong enough to trip “sensory-specific satiety,” a neural signal that makes you think you’re full.

The D.L.T. became a flash point in food engineering. “Once we had the learnings gained from developing the Doritos taco shell,” Lefebvre said, it paved the way for “collaborations like the Taco Bell Fritos Taco.” Anyone who has ever put potato chips on a sandwich can appreciate the appeal of a burrito with Cheetos inside, or a Cheez-It deployed as a raft for spicy meat.

The new taco was tested out at a few of the chain’s locations. “People were driving three hundred miles to get the D.L.T.,” Matthews said. “One guy drove across the country.” The product was officially launched in 2012, and a hundred million Doritos Locos Tacos were sold in the first ten weeks. A 2013 marketing case study singles out Taco Bell’s plan to “create a subculture of Doritos Locos Tacos fanatics.” Sean Tresvant, a Taco Bell branding director, told me that the company’s mission is to “build content for cultural rebels.” It’s no accident that the flurry of new-product launches, which in the trade have come to be known as “stunt food,” has tracked precisely with the rise of social media.

In a salt-and-fat-based arms race, chains now compete to roll out bizarre and often revolting novelty decoys to seduce customers. In the futuristic 1993 movie “Demolition Man,” Taco Bell is, in 2032, the only fast-food chain left after a series of corporate battles called the Franchise Wars. The movie was prescient. The years since then have given us Burger King’s Bacon Sundae, Pizza Hut’s hot-dog-stuffed crust, Cinnabon’s Pizzabon, and KFC’s fried-chicken-flavored nail polish (“finger-lickin’ good”). Taco Bell remains determined to out-stunt them all.

The Crunchwrap Supreme, Lois Carson’s magnum opus, is a tortilla-wrapped parcel of seasoned ground beef, nacho-cheese sauce, crunchy tostada shell, lettuce, tomatoes, and sour cream. It is 1.25 inches tall, six inches wide, and 6.25 ounces. When it débuted, in 2005, it sold fifty-one million units in the first six weeks. The food critic Adam Richman suggested that Carson should be nominated for a Nobel Prize. At our meeting in Orange County, Carson bashfully took from her bag a framed copy of an article in Nation’s Restaurant News about the Crunchwrap’s launch. It quoted a “junior burrito analyst” from burritoblog.com saying, “I had five of these puppies the first week they were available. The new Crunchwrap Supreme has taken the hard/soft texture idea and advanced it.”

Carson sat in silence for a moment. “In the beginning, there were people who didn’t like the idea,” she said. “But somewhere in my mind I knew—it was portable, it was crunchy and soft, there was the price point, it meets sensory needs, it’s easy to eat. It may have been before its time.”

Prior to its success, the Crunchwrap idea languished for thirteen years. “Think about that fold! It had never been done,” Matthews told me in the lab. “Lois would show it at every meeting. They thought she was insane. Everyone else was, like, ‘Oh, God. Here she goes again.’ ” Greg Creed was the fifth chief marketing officer to hear her spiel, and he was looking for pitches with a visual twist. The Crunchwrap checked that box, and others. It qualified as functional, “something that allows us to multitask and doesn’t require utensils or our full attention to enjoy,” as he put it—the caloric equivalent of a sitcom that’s on in the background while you fold laundry. It obeyed Taco Bell’s sacrosanct Distinctiveness Rule: “You can change either the taste or the form” of a beloved food item, Creed said. “But you can’t change the taste and the form.”

When Carson showed Creed her Crunchwrap in the lab, he got it. By then, she was using a larger tortilla and heat-sealing it in a panini press to keep it closed. Soon, the Crunchwrap was starring in a Taco Bell ad campaign, with the tagline “Good to go!” The commercials compared the Crunchwrap to other engineering marvels, like smart watches and newfangled MP3 technology.

“I honestly want him to be happy—just not in a way that I’ll ever have to find out about.”

To celebrate, a friend gave Carson a box of origami paper, a reference to her folding genius. Two years after the Crunchwrap’s launch, another friend, who worked at Mars Inc., encouraged Carson to file a patent. At her urging, Taco Bell hired lawyers, who submitted an application for “Comestible wrap product and method of making the same.” Patents for fast food read like a mashup of ikea assembly instructions and post-structuralist literary theory—pages and pages of annotated drawings, followed by dense analyses of individual figures. In Carson’s abstract for the patent, she details why her product is a necessary alternative to a traditional tostada, in which “the beans, sauce, lettuce, and cheese are vulnerable to sliding off the tortilla shell and/or to getting wiped off the tortilla shell by a bag, a clothing item such as a customer’s sleeve, or by some other object.” The patent notwithstanding, the Crunchwrap is the sole property of Taco Bell, and Carson received no remuneration for it beyond her salary.

Carson is glad that she persisted with her vision. “It’s the chemical reaction of the heat and the starch in the tortilla that makes it stick together,” she said. “So that’s science itself.” She’d also put in time trying to solve the puzzle of the Doritos Locos Taco. She drew a triangle on a piece of paper and showed it to me. “In ideation, I don’t use the word ‘never,’ but I thought it probably wouldn’t work,” she said. “The tip of the triangle will break—it’s a fragile point up top.” She drew a traditional semicircular taco shape next to the triangle to indicate what the D.L.T. evolved into. She always had a feeling that it would end up there. “But, still, we said, ‘Tortilla supplier, we would like you to make this for us.’ They said I was crazy. But they’d ship it to California, and we’d try to put ingredients in it.”

To release about ten new products a year, Taco Bell’s innovation scientists test roughly seventy; to come up with those seventy, they consider thousands of ideas. Matthews regularly takes groups of employees on food-immersion trips to cities around the world, where they eat for four days. “Then there are text chains, Slack chats, voice memos in the middle of the night about potatoes,” she said. Others spoke of “ideation sessions.”

Developing the right products is just one aspect of the work; marketing them is a separate task. Matt Prince, the company’s public-relations director, handles brand development and what he called “cultural topspin.” He talked about Taco Bell’s impact on the nation’s agricultural system. Say someone pitched a new item that contained parsley, he said.“When you multiply and scale it, you could then deplete the country and the supply chain of parsley.” He stopped and corrected himself: “Sorry, I mean cilantro.” He went on, “So is it worth it?” With other items, the company takes a watch-and-wait approach. “Popeyes and Chik-fil-A had the sandwich wars over fried-chicken sandwiches,” he said. “Chicken never played a huge part on our menu, but now there’s a huge spike in how we’re leveraging chicken.” He was referring to Taco Bell’s Naked Chicken Chalupa, in which a flat piece of fried chicken is used as a taco shell. One member of the innovation team envisions twisting fried chicken into an ice-cream-cone shape and serving it filled with ranch dressing.

“We’re balancing familiarity with innovation,” Prince said. “Like, when we had avocado in breakfast items, you look at the heartland and that wasn’t resonating.” Taco Bell fans are forthcoming about their preferences. Krish Jagirdar, who circulated a Change.org petition to bring back Mexican Pizza, said, “It’s one of the few food items that I really do care about. The petition gave me agency and connection.” The leader of the movement to bring back the Beefy Crunch Burrito texts Prince regularly. “Sometimes I wish I were as passionate about something as people are about this burrito,” Prince said.

Taco Bell has invested in all kinds of schemes to manufacture the passion. There are Taco Bell Cantinas, with liquor licenses, including the Pacifica Cantina, in California, a high-end oceanfront location equipped with a fireplace. (Before the concept launched, beer milkshakes were tested.) There is a travelling drag-brunch series, a Taco Bell wedding chapel in Las Vegas, a line of N.F.T.s, a Taco Bell TikTok musical starring Doja Cat. Conan O’Brien did a segment on visiting the Innovation Kitchen. Then there’s the Bell Hotel, in Palm Springs, a weeklong resort “experience,” featuring synchronized swimming and superfans gorging on new Taco Bell products. (The beds in the rooms are strewn with chips, as if they were rose petals.) “It was chaos,” Pisciotti said of the last event. “There was a person there with their hair dyed Baja Blast blue. It took them months to get the right color. They’re fanatics. But hate and love are better than indifference.”

The company is sensitive to feedback. The headquarters has a situation room called the Fish Bowl, ringed by video screens monitoring the brand’s mentions on social media. In 2015, in response to consumer requests, the company removed artificial colors and flavors from its menus, and it now uses cage-free eggs. Nineteen years after the documentary “Super Size Me” conditioned Americans to equate fast food with pink slime, Taco Bell has, through the power of marketing, managed to make itself not just socially acceptable but post-ironically hip.

Last year, the company opened a “Jetsons”-like four-lane drive-through in Minnesota called Taco Bell Defy; a proprietary techno-dumbwaiter whooshes tacos down to car windows from an overhead kitchen. “I’m a low-cost provider of food to the general public,” the store’s franchisee, Lee Engler, said, “but this is twenty-second-century stuff.”

“It’s a cry for help in the hellscape,” M. M. Carrigan, a writer in Baltimore who edits the online literary journal Taco Bell Quarterly, said. “There is this perpetual renewal to their menu items. They keep making these novel items for us, shape-shifting—like, we’re going to give it to you in a hotel in a Crunchwrap, we’re going to give it to you through tubes into your car, we’re going to give it to you in the Metaverse. It’s the illusion of progress.” Or it’s the logical endgame of American abundance and choice, the marketing apex of what Michael Pollan describes, in “The Omnivore’s Dilemma,” as “what the industrial food chain does best: obscure the histories of the foods it produces by processing them to such an extent that they appear as pure products of culture rather than nature.”

The Orange County location where I met Carson is just down the road from the Innovation Kitchen, and not far from Glen Bell’s first taco stand. A blind man in a Nirvana T-shirt with a service dog sat alone in a booth drinking a Freeze, and two employees from a neighboring pastrami drive-through came in to order breakfast. When the Crunchwrap launched, Carson and a colleague often visited this location to observe undercover. “We would get the Crunchwraps and weigh them, pull them apart in stealth,” she said.

Most days during Carson’s time at Taco Bell, she brought a lunch of fruit and yogurt or a peanut-butter sandwich to work, until she was laid off in a standard round of job cuts, in 2008. (She continued working for the company, as a food-photography consultant, and for the past fifteen years she has run a successful business as an executive coach.) “I worked on almost every single ingredient at Taco Bell,” she said. After years of testing fried foods, she is exquisitely attuned to the taste of rancid oil. “Your taste buds get trained,” she said. “Your mind becomes educated.”

Carson is generally circumspect, but she became animated when she talked about a recent novel called “Lessons in Chemistry,” by Bonnie Garmus. It’s the story of Elizabeth Zott, a frustrated chemist in the nineteen-sixties who ends up hosting a cooking show. Like Carson, Zott sees a sacred geometry in recipe design. At one point, she tells her viewers, “A successful chicken potpie is like a society that functions at a highly efficient level.”

I asked Carson if she wanted to order a Crunchwrap. “If they can get it to us in time,” she said. She had to leave for a coaching session. An employee at the register sold me on a deal: instead of a Crunchwrap for four dollars and ninety-nine cents, I could get a Crunchwrap with a Doritos Locos Taco and a Baja Blast for five dollars. Fifty seconds later, I brought it all back to Carson on a tray.

“It’s not grilled enough, and the fold is a little sloppy. And it’s got grill dirt on it,” she said of the Crunchwrap. After I took a bite, she examined the interior composition by prodding it with a fork. I asked if she wanted to try it. She declined. She has always liked the taste of Taco Bell, but eating it regularly was a busman’s holiday. “I don’t eat in my car,” she’d told me. “I wouldn’t go through the drive-through of a restaurant.” ♦