From there, it’s a ponderous journey over concealed but intense flames that toast first one side, then the other as the tortillas flip and return to the far end of the machine. When man and machine are in sync, they can produce as many as 7,500 tortillas per hour, most to be sold from the doorway or delivered by bicycle to nearby street vendors and homes.

I’d come to Mexico City to learn about its tacos, a food ubiquitous to Mexico but revered in the capital, where street vendors ply innumerable varieties from dawn well into dark. And Ledezma quickly illustrates how little I know. Pulling a fresh tortilla from a stack, he sprinkles it with salt, folds it in half, tilts his head to the side and devours it in two quick, satisfying bites.

That’s a taco, he explains. Wait... What? Isn’t that just a... soft tortilla chip?

So is this, he adds, grabbing another tortilla and using it to pull hunks of meat from the chicken that was cooked on the tortilla maker. He spoons a thick, deeply charred, almost black salsa over it, then repeats the fold-tilt-eat maneuver. “It tastes of Mexico,” he says. “The corn, the soil, the families and memories.”

I follow his lead, repeating both of his tacos. The first is sublime in its simplicity, the essence of corn—warm, sweet and lingering—though it hardly seems a taco. The second is ridiculously satisfying, savory and spicy. Both are a long way from the crunchy taco “shells” stuffed with vaguely spiced ground beef, lettuce and watery tomato salsa I disliked as a child.

There were many lessons hidden in this exchange. The balance of flavors and textures. The importance of the tortilla itself. The interplay of fire and smoke. The role of dried chilies. Even the method of eating. But they’d only reveal themselves slowly as I spent the week scouring the city for great tacos. Clearly, I had much to learn.

The Corn

Some parts of the U.S. are lucky enough to have a true taco culture. Many are not, the only viable explanation for the sad state of the tacos many of us know. So an explanation is in order. The exact origins of the taco are debated, but most agree they date back in some form to Mexico’s pre-Hispanic period, when tortillas were used to scoop food.

The modern taco hit its stride in the early 20th century, when rural workers moved to the cities, especially Mexico City, bringing varied foodways and opening streetside stands to feed fellow migrants looking for a taste of home. Today, the city has nearly 20,000 taquerías, and one study found that almost nobody lives more than 400 meters from a taco stand.

But what is a taco? “You can make a taco with anything,” says María Ítaka, my translator. “If you have a tortilla and a filling, you have a taco. The moment you fold it up, that’s a taco.” That salt taco, for example. It’s Mexico’s answer to England’s beans on toast, or the United States’ cold breakfast cereal for dinner. And, of course, that’s just the start.

And it all begins with corn. Tougher and more flavorful than sweet American corn, Mexican corn must be soaked, then cooked in a lime solution. This process, called nixtamalization, plumps and tenderizes the kernels, rendering them digestible. They then are stoneground to form masa, a soft, moist dough that is easily shaped.

The smell of that dough—and tacos in Mexico City almost always are made with soft corn tortillas—flattened and cooked on griddles called comals, fills the city’s streets with toasted sweetness, mingling with sizzling meat, cilantro, pops of lime, all of it perfumed from jacaranda trees that canopy the streets with purple flowers that smell of honey, ivy and rain.

And it’s on those streets where my taco education begins in earnest.

The Method

Tacos can be a workout. To make his point, Ruben Orozco breaks the staccato of his knife chop-chop-chopping charred beef and chorizo on a well-grooved cutting board to hold up both hands. His right is significantly larger than the left. He has worked as a butcher since he was 8; he has run Tacos Ruben’s with his wife, son and daughter for 16 years.

His stand is parked on a sidewalk across from a gas station, a soccer match playing on a television hanging from the rafters of his canopy, a dozen people lined up waiting. The family works in unison to produce tacos suadero—citrus-marinated beef cooked with tripe in chorizo fat on a sombrero-shaped comal, or chorizera, finely chopped and slid onto double layered tortillas.

Onions, cilantro, lime. Four salsas of varying heats and complexions are holstered along the side of the stand for diners to help themselves. All of it, just a few pesos apiece. Handed one, I fold it and bring it to my mouth. Rich and meaty, bright, fruity and fresh. Wildly flavorful. Or at least the parts of it that don’t land on my shirt and shoes are.

That’s my next lesson. The contents of the taco may be flexible, but the art of eating it is more rigid. Orozco shakes his head at me. The taco does not come to you, he says. You go to the taco.

He grabs a taco suadero, pinching the tender corn tortilla closed with thumb and forefinger, pinkie extended. He tilts his head to the left, his open mouth now mimicking the shape of the taco, then—without moving his hand—brings his mouth to it, eating it in two generous bites. When he smiles, the crowd nods along. This is how you eat a taco, they agree.

The Flavors

Clear on what a taco is and how to eat it, I’m ready to cook one. My lessons begin in the sprawling, sunny kitchen of Jorge Fritz and Beto Estúa—charming husbands, designers and cooking instructors in the artsy Roma Norte neighborhood. The evening ends with enough mezcal to render my later notes less helpful than I’d like.

In between, there are tacos. So many tacos. We buy the tortillas from a vendor at the nearby market, allowing us to focus on the fillings. And here, no matter the protein, it is a lesson of contrasts. The backbone of nearly every taco I eat in Mexico City is a delicious flavor tug-of-war between bright citrus and earthy-fruity dried chilies.

We start with cochinita pibil, a pulled pork from the Yucatán—a mix of loin, shoulder and rib—cooked in a smooth sauce of sour orange juice, habanero chilies, red onion, earthy-peppery achiote paste (a blend of bold red achiote seeds and chilies), allspice and avocado leaves.

Traditional versions cook many hours, but Fritz and Estúa opt for the pressure cooker, readying the pork in under an hour. The meat then is fried in a skillet with more red onion. It’s a wonderful technique that allows the meat to first become fall-apart tender without drying out, then creating richness and texture from a speedy char.

Spooned onto warm corn tortillas—“Corn is at the center of our culture and heritage. It shaped us and who we are,” says Fritz. “Oh, and chilies!”—and topped with pickled red onions and a salsa of deeply charred chilies, garlic and onion, the tacos are bright, tangy and porky, at once warm and citrusy. So many layers.

Next, fish tacos, too often a fried mess in the U.S. In Fritz and Estúa’s hands, they contain tender, brightly seasoned mounds of red snapper chunks marinated in a puree of orange juice, white onion, leathery guajillo chillies, oregano, cumin and achiote paste. The fish cooks in minutes, staying tender and juicy.

But the magic is in the toppings. This is where we so often get it wrong. Great tacos are about balancing taste and texture.

So to balance all the richness, we make a quick pickle of diced carrots, celery, onion and pineapple that is cooked until the liquid is pulled out, then evaporates, the sugars left behind caramelizing and thickening. It is tangy and sweet and a little chewy. Paired with a salsa fresca of pureed tomatillos, white onion and serrano chilies, the result is a riot of fresh citrus balancing chili-­savory snapper, all tucked in a warm, pillowy soft-sweet tortilla.

With both tacos, there is so much happening, so many flavors and textures to tease out, you hope there never is a last bite. And in each case, it’s that same signature push-­pull of bright citrus balancing fruity-earthy dried chilies.

With the salsa set, Méndez—who learned her recipes from her mother and grandmother—assembles tacos gobernador, shrimp tacos supposedly created 30 or so years ago by a restaurant hoping to impress a Mexican governor. It’s an unusual combination of shrimp, tomatoes and mozzarella-­like quesillo cheese. It’s as delicious as it is simple.

Tomatoes and onions cook in a skillet until they char just a bit, then break down. Plump raw shrimp are tossed in, cooking mostly in the residual heat of the vegetables. Meanwhile, Méndez sprinkles shredded cheese onto the top of a tortilla, then quickly flips it cheese side down into a hot skillet, rubbing it around until the cheese melts and browns in spots.

With a quick flip, she overturns the tortilla, the cheese now a delicious sticky mess, then spoons the shrimp mixture onto it. Little to no seasoning is needed—that comes from the salsa. The finished taco is amazing. Spicy and jammy, briny with plump shrimp, creamy and rich with toasted cheese. And it all took roughly 20 minutes.