MEXICO CITY — Newly minted Michelin-starred chef Arturo Rivera Martínez stood over an insanely hot grill Wednesday at the first Mexican taco stand ever to get a coveted star from the French dining guide, and did exactly the same thing he's been doing for 20 years: searing meat.

Though Michelin representatives came by Wednesday to present him with one of the company's heavy, full-sleeved, pristine white chef's jackets, he didn't put it on: In this tiny, 10-foot by 10-foot (3-meter by 3-meter) business, the heat makes the meat. And the heat is intense.

At Mexico City's Tacos El Califa de León, in the scruffy-bohemian San Rafael neighborhood, there are only four things on the menu, all tacos, and all of which came from some area around a cow's rib, loin or fore shank.

''The secret is the simplicity of our taco. It has only a tortilla, red or green sauce, and that's it. That, and the quality of the meat,'' said Rivera Martínez. He's also probably the only Michelin-starred chef who, when asked what beverage should accompany his food, answers ''I like a Coke.''

It's actually more complicated than that. El Califa de León is the only taco stand among the 16 Mexican restaurants given one star, as well as two eateries that got two stars. Almost all the rest are pretty darn posh eateries (hint: a lot of expensive seafood served in pretty shells on bespoke plates).

In fact, other than perhaps one street food stand in Bangkok, El Califa de León is probably the smallest restaurant ever to get a Michelin star: Half of the 100 square-foot (9.29 square-meter) space is taken up by a solid steel plate grill that's hotter than the salsa.

The other half is packed with standing customers clutching plastic plates and ladling salsa, and the female assistant who rolls out the rounds of tortilla dough constantly.

In a way, El Califa de León is a tribute to resistance to change. It got there by doing exactly the same four things it has been doing since 1968.

Thousands of time a day, Rivera Martínez grabs a fresh, thinly sliced fillet of beef from a stack and slaps it on the super-hot steel grill; it sizzles violently.

He tosses a pinch of salt over it, squeezes half a lime on top, and grabs a soft round of freshly rolled tortilla dough onto the solid metal slab to puff up.

After less than a minute — he won't say exactly how long because ''that's a secret'' — he flips the beef over with a spatula, flips the tortilla, and very quickly scoops the cooked, fresh tortilla onto a plastic plate, places the beef on top and calls out the customer's name who ordered it.

Any sauces — fiery red or equally atomic green — are added by the customer. There is no place to sit and at some times of day, no place to stand because the sidewalk in front of the business was taken over by street vendors hawking socks and batteries and cell phone accessories years ago.

Not that you really would want to eat inside the tiny taco restaurant. The heat on a spring day is overwhelming.

The heat is one of the few secrets Rivera Martínez would share. The steel grill has to be heated to an astounding 680 degrees (360 Celsius). Asked how it felt to get a Michelin star, he said in classic Mexico City slang, ''está chido ... está padre,'' or ''it's neat, it's cool.''

The prices are quite high by Mexican standards. A single, generous but not huge taco costs nearly $5. But many customers are convinced it's the best, if not the cheapest, in the city.

''It's the quality of the meat,'' said Alberto Muñoz, who has been coming here for about eight years. ''I have never been disappointed. And now I'll recommend it with even more reason, now that it has a star.''

Muñoz's son, Alan, who was waiting for a beef taco alongside his father, noted ''this is a historic day for Mexican cuisine, and we're witnesses to it.''

It really is about not changing anything — the freshness of the tortillas, the menu, the layout of the restaurant. Owner Mario Hernández Alonso won't even reveal where he buys his meat.

Times have changed, though. The most loyal customer base for El Califa de León originally came from politicians of the old ruling PRI party, whose headquarters is about five blocks away. But the party lost the presidency in 2018 and has gone into a steady decline, and now it's rare to see anyone in a suit here.

And Hernández Alonso noted that his father Juan, who founded the business, never bothered to trademark the Califa name and so a well-funded, sleek taco chain has opened about 15 airy restaurants in upscale neighborhoods under a similar name. Hernández Alonso has been toying with the idea of getting the business on social media, but that's up to his grandkids.

By law, following the coronavirus pandemic, Mexico City restaurants have been allowed to open up street-side canopied seating areas. But El Califa de León doesn't even have a sidewalk for customers to eat on because of all the street vendors, so customers now stand cheek-to jowl with display stands and plastic mannequins.

Asked if he would like them to make room for a street-side seating area, Hernández Alonso expressed an ''if it ain't broke, don't fix it'' attitude.

''As the saying goes, why fix or change something that's alright? You shouldn't fix anything,'' he said, motioning to the street vendors. ''It's the way God ordered things, and you have to deal with it.''