As a kid growing up in Hermosillo, the biggest city in the arid northern Mexican state of Sonora, Ruben Leal took the region's signature flour tortillas for granted. You could find them not only in tortillerias -- where veteran makers would flip them, sometimes bare-handed, on a ripping-hot comal -- but also at any of the city's abbarotes, or corner stores, where "they have fresh ones that the tortilla lady dropped off early in the morning," Leal told me. Tortillas de harina, made with freshly milled wheat and pork fat or vegetable shortening, were essential for staples like tacos, burritos, and caramelos -- a Sonoran quesadilla made with carne asada -- but they were also delicious enough to eat plain.

In 2002, Leal moved to Tucson, where he studied marketing at the University of Arizona and met the woman he would marry. They moved to Austin, where Leal got his tortilla fix at the Texas grocery chain H-E-B, which makes them fresh. A few years later, the couple moved again, this time to Lawrence, Kansas, a college town some forty miles west of Kansas City, not far from where Leal's wife grew up. The area's Mexican population is relatively small, and the dish known as the "Kansas City taco" is a mid-century relic: a deep-fried, hard corn shell with ground beef, shredded lettuce, and cheese powder. "I kept getting farther away from the border and the tortillas kept getting worse," Leal told me recently, standing in the Lawrence headquarters of his company, Caramelo, which has lately emerged as one of the best producers of tortillas in the U.S.

In the center of a cavernous room, an employee was loading dozens of golf-ball-size mounds of dough into an enormous machine reminiscent of an early printing press, outfitted with hot steel plates that flattened and cooked them, then spat the finished products onto a long mesh conveyor belt. A floor fan cooled the tortillas -- Caramelo produces some fifteen thousand flour tortillas a day -- as they were ferried to a packaging station. Leal, who is forty, tall, and broad-shouldered, with a pair of delicate nose rings and a low ponytail, plucked one off the belt and handed it to me. It steamed gently as I bit into it -- stretchy, supple, and gossamer-thin, pocked with bubbles and rich with the creamy tang of animal fat.

The night before, I'd eaten a burrito, made with a Caramelo tortilla, at a Kansas City restaurant called Tacos Valentina. I told Leal that the tortilla -- which was charred and filled with beans and chile-colorado-stewed pork -- was almost as flaky as a laminated French pastry. Leal, laughing, said, "Yeah, some people call them the croissants of tortillas." His machinery is customized to allow for exacting temperature control. "Because our tortillas are very specific, a lot of machines don't like them," he said. "They puff up really easily, because of the water and fat content." Containing the heat means that the tortillas keep their structural integrity, though, to Leal's chagrin, it sacrifices the burnished freckles you'd see on a handmade version.

Leal decided to try making his own tortillas in 2014, on a day when he felt particularly homesick and bored by his job, as an administrator in the chemistry department at the University of Kansas. His first attempt, guided by a YouTube video, missed the mark on both flavor and texture, but he got the general idea: mix, roll, flatten, cook. "I didn't know I liked working with food until I moved to Kansas," he told me. As he experimented with different proportions of flour, water, salt, and fat, he became obsessed. After his mother died, in 2016, he claimed an old tabletop electric tortilla press from her kitchen in Hermosillo; the tool gave his tortillas the uniform shape and texture he'd been looking for, and also allowed him to dramatically increase his output. He began to wonder if he could sell them.

Before he had bags or a logo, Leal met with buyers at the Merc, Lawrence's coöperative grocery store, toting a tortilla warmer full of freshly cooked samples. The buyers immediately agreed to start carrying them. Not long afterward, he offered samples to Alejandra de la Fuente, a native of Mexico City and the chef and owner of a Kansas City restaurant called Red Kitchen. She had been hunting as far as Denver for a fresh flour tortilla that met her standards, and was on the verge of giving up. "As soon as he pulled out the tortilla, I was, like, 'That's exactly what I was looking for,' " she told me. Soon, Leal was on the hook for dozens of tortillas a week. After clocking out from his day job, he would spend hours at a rented commercial kitchen, and then continue making tortillas at home, sometimes until 2 a.m. "My wife was, like, 'Why is it so smoky in here?' " he recalled. (They're now amicably divorced.)

Today, Leal supplies tortillas to restaurants, specialty shops, and home cooks around the country, in a range of sizes and made with a variety of fats, including avocado oil and duck fat. Many of his clients are in New York, including the Mexican master chef Enrique Olvera, who uses them at Esse Taco, his Brooklyn taqueria, for burritos stuffed with grilled rib eye or smoked mushrooms. When I asked Olvera what he liked about the Caramelo tortilla, he shrugged as if it were obvious. "It's like getting a warm hug from your grandmother," he said. Leal told me proudly, "One of the most flattering things is that restaurants from Mexico are setting up businesses in the U.S., and they're reaching out to us for tortillas. And they even tell us that ours are better than what they're getting down there."

For much of my life, I was a corn-tortilla partisan. All the exceptional tortillas I'd eaten were made from sweet, nutty masa, the base for the tantalizingly restrained tacos you might get at a street cart, with just a scattering of carnitas, onions, and cilantro. I associated flour tortillas with maximalist dishes at middling Tex-Mex restaurants, and with the "ethnic" aisle at the grocery store, where the offerings are mostly pale and doughy, packed with preservatives that rob them of texture and flavor. That changed when I visited a taqueria in L.A. called Sonoratown, opened in 2016 by Jennifer Feltham and her husband, Teodoro Diaz-Rodriguez, Jr., a native of Sonora. (The name also refers to the bygone L.A. neighborhood of Sonoratown, where a community of Mexican immigrants settled after the Gold Rush.) The tortillas there, made with flour that Feltham was commuting to Mexico every week or so to buy, redefined the form for me: chewy and pliable, so thin they were nearly transparent, salty and shiny with luscious pork fat. To eat only one would have felt like torture.

Feltham and Diaz-Rodriguez have bonded with Leal over their shared passion. "I'm drawn to people that are obsessed with one thing, like the guy who does our chorizo," Feltham told me. "When we first met, he was, like, 'I'd love to have a girlfriend, but I have so much chorizo drying in my apartment right now that I wouldn't have anywhere to bring her.' " As tacos have become central to U.S. food culture, they've come to inspire the kind of connoisseurship once reserved for wine and cheese. José Ralat, who serves as Texas Monthly's taco editor, is one such expert. He told me that a defining quality of a Sonoran tortilla is "gauziness -- I can see the sun through them." Recounting a recent visit to Hermosillo, he said, "The tortillas there are an amazing vessel, because they're so thin yet so strong. They bear so much weight, not only with the food but with the history."

In pre-colonial Mexico, corn was beloved by, and even sacred to, Indigenous populations, including the Aztecs. But Spanish settlers favored wheat, which was native to the Fertile Crescent, and which they associated with the Eucharist. In northern Mexico, this bias, combined with a climate that was better suited to growing wheat than corn, resulted in the ascendance of the flour tortilla. Across the border in Texas, and in other parts of the Southwest, flour tortillas bear a range of regional quirks. Ralat described "the equally beautiful, thick, chewy, futon-like San Antonio tortilla," which he likened, affectionately, to warm laundry.

As it happens, Leal is not the only producer of Sonoran-style tortillas in the Kansas City area. By coincidence, Marissa Gencarelli, who was born and raised in Obregón, the second-biggest city in Sonora, started a tortilleria in 2016, called Yoli, with her husband, Mark, a Kansas City native. The two companies seem to enjoy a healthy sense of competition, on which both founders, in Midwestern form, politely declined to comment. The Gencarellis started with corn. After they added flour to their repertoire, Leal added corn to his. Both companies recently began offering totopos, or corn chips, which share shelf space at the Merc. Last fall, the Gencarellis, who won a James Beard award in 2023, introduced a café and shop called Yoli Loncheria; Leal is preparing to open his own burrito counter, called Ignacio, after his Mexican hairless dog.

Gencarelli told me that she sees similarities between Kansas City and Obregón, both of which have "a little burr in their belly" from being in the shadows of bigger cities, and are known for agriculture, especially wheat. "The temperament is very similar, confident but understated," she said. "Like, yeah -- laugh about us, tell us that we're flyover country, but it's O.K. We know what we got." Leal has remained in Lawrence for practical reasons -- he and his ex have two children, and it's cheaper to keep up with mounting demand for his tortillas than it would be in Austin or New York -- but he's come to see it as home. During my visit, Leal and I drove in his vintage Jeep to 1900 Barker, a coffee shop on Lawrence's main drag. Leal got what he described as "a McDonald's breakfast sandwich on steroids." I tried to order a breakfast burrito, made with a Caramelo tortilla, but they were sold out. Leal confessed that he "very rarely" eats tortillas these days. "They're here now," he said, laughing, "so I'm used to it." ♦