LOS ANGELES >> Bar A Tí is a serious taqueria: fresh blue-corn masa, a dark and cryptic mole that ferments for a full school year, duck confit, the works. The crispy taco, however, is a crinkled half-moon of braised beef shank flickering with garlic, chiles and cilantro under a heavy fringe of neon orange cheese.

This is not, at a glance, a serious taco. Though Andrew Ponce uses thin Kernel of Truth tortillas for his crispy tacos, and excellent tomatoes for the salsa, he also invokes the tacos of Cal-Mex diners, fast-food chains and family meal kits. He calls back, with some nostalgia, to the American hard-shell tacos that thrived in midcentury California and, for better or worse, shaped the iconography of tacos around the world.

Ponce, a Mexican American chef who opened restaurant in Los Angeles’ Echo Park neighborhood about a month ago, grew up in Culver City, and when he wanted to go out for crispy tacos at Taco Bell or his local spot Tito’s Tacos, his father disapproved. Hard-shell tacos were a goofy and inauthentic misunderstanding. Besides, the family had real Mexican food at home!

“I wasn’t supposed to have it,” Ponce said, “and that made it so much better.”

Los Angeles is in fact heaven for the crispy-taco lover — delicate pescadillas over black beans from Simón and fish flautas from Ditroit. Habit-forming tacos de camarón from Mariscos Jalisco and extra-long potato and chorizo flautas from Los Dorados. The crispy tacos at Los Garduños, filled with sticky lamb barbacoa from the cooler, are almost hidden under iceberg and queso fresco, and make a rehabilitating weekend breakfast.

At Chuy’s, Betsy Leon sells tacos dorados that she learned to make from her father as a teenager, approximations of the ones her great-grandparents used to make at their restaurant in Culiacán, Mexico, filled with mashed potatoes and covered with onions pickled in lime juice. Cielito Lindo, on Olvera Street in LA, has been frying tiny beef-filled taquitos and drenching them in avocado salsa since 1934.

But I turned my attention to the Americanized version that Glen Bell of Taco Bell made internationally recognizable. This subgenre can be found at the old, slightly dusty fast-food stands that might have once competed with Taco Bell, but now seem like museums of an unlikely regional treasure.

On a recent Monday, as Suvit Sirikulbut tried to get through his morning to-do list at Taco Fiesta in Highland Park, he was interrupted several times by customers who ducked their heads and shouted his American nickname under the glass: “Hi, Sam!” He waved them away, a bit grumpily. He had about 30 more tortillas to fry into perfect U-shaped shells.

Sirikulbut emigrated from Nakhon Si Thammarat, a city in southern Thailand, in the late 1960s and has been frying tortillas at his tiny food stand in the back of a supermarket parking lot since 1972.

When he bought the business, he’d never eaten a taco and didn’t know or care how to cook. What he did know was that investing in a local business was part of his plan to stay in the country. So why not this one?

A regular who lived in the neighborhood walked Sirikulbut and his wife through the menu, dish by dish, explaining how each was supposed to taste. Sirikulbut, who is now 81 and has no succession plan, has been an inadvertent guardian of this culinary artifact in Los Angeles for more than 50 years.

My neighbor in Highland Park grew up calling Sirikulbut’s tacos, with some affection, “Brady Bunch tacos.” You may have heard other terms, like “middle school tacos,” “lunch lady tacos” or “gringo tacos.” Tim Walz has called the Midwestern version he makes at home “white-guy tacos.” Though the appeal of the hard-shell taco is cross-cultural and intergenerational, the way we name it obscures its origins.

At Al and Bea’s in Boyle Heights, a no-nonsense shop open since 1966, a line starts to form before it even opens. The crispy tacos look exactly like those midcentury hard shells, but they’re fried to order. Customers in construction gear, or button-down shirts and shiny lanyards queue by the door with cash and handwritten group orders in hand.

On a recent Tuesday, a cook wheeled by with a large, squeaky cart.

It was full of rows of chubby tortillas bundled in plastic wrap, each one filled and folded, pierced with a toothpick to help keep it shut when it was dropped in hot fryer oil. All day, these would be cooked until crisp, then topped with iceberg, cheddar and a fat wedge of raw tomato.

On the menu, they appear simply as “tacos.”