The restaurant was closed on Monday, but the patio was buzzing.

Outside little South Philly Mexican restaurant El Chingon, a taqueria and sandwich shop named this year among the 50 most exciting restaurants in the country by the New York Times, every sidewalk table was full. Conspicuously well-dressed couples had begun to loiter by the kitchen window.

Finally, the window opened at the side of the restaurant, and a little box slid out. Inside was a perfect circle of oven-blistered and long-proofed crust under a blanket of tomatillo sauce and melted Chihuahua cheese, adorned with slow-braised carnitas and mezcal-spiked borracho salsa. Sprinkled atop, like a chef’s kiss from Salt Bae, was a scattering of the same raw onions and cilantro you’d find on any old taco.

Mexican pizza had finally arrived.

In South Philly more densely than perhaps anywhere in the country, Mexican pizza is a treasured local cuisine — a specialty for a dozen restaurants within a mile or two of each each other. By now it’s also a regional food, found from Wilmington, Delaware, to South Jersey and Bucks County.

The story of the city’s Mexican pizza goes back eighteen years, to a chef by the name of Valentin Palillero who first learned to make pizza at an airport. It is also the story of two tiny towns in Mexico, and a century of immigration in South Philly.

First, the Southern Italians came, eventually bringing with them an unfamiliar food by the name of “pizza.” In more recent decades, a new generation of chefs arrived from the state of Puebla in Mexico. Many ended up in Italian restaurant kitchens, learning firsthand the meticulous art and obsession of pizza dough, and adding their own twist. 

When Mexican chefs signed leases to open restaurants in a South Philly neighborhood long dominated by Italian American restaurants, many found pizza ovens already installed. The results were, perhaps, predictable.

But for at least a decade, Mexican pizza in Philadelphia remained a mostly underground phenomenon, reserved to shoebox-sized bodegas and late-night delivery spots. 

Lately, that’s begun to change.

El Chingon chef Carlos Aparicio was floored by Philadelphia’s hunger for Mexican pizza. He’d planned a one-day pizza pop-up on July 31, as a nostalgic return to his years as head chef of lauded Philadelphia Italian spot Zavino. There, he’d often served pizzas with Mexican flavors as off-menu items.

Now customers won’t stop bothering him about it.

“Everyone keeps asking me. ‘When do I want to do it again? When will I do it again?’” Aparicio said. “What should I call it if I do? Do I have to give it a name?”

Mexican pizza comes into the limelight, and spreads from South Philly to South Jersey and Delaware

Eighteen years into its existence in Philly, Mexican pizza is having a bit of a moment.

At least five new Mexican pizza shops have opened in South Philly alone in the past couple years. The al pastor pizza gospel has traveled to Wilmington, Delaware, where a little takeout spot called Tacos and Pizza House serves earthy-spiced al pastor on both of its namesake foods. On a patio in Westville in South Jersey, La Tentacion offers trendy beef birria pizza with a side of consome for dipping. 

Popular South Philly takeout spot Rosario’s Pizzeria has expanded into neighboring Montgomery County this year, opening a second location in Cheltenham with a dozen options on Mexican-inspired pizza. 

Bucks County breweries like Neshaminy Creek get regular visits from an accomplished wood-fired mobile kitchen called Victor’s Pizza Truck. Its chef, Victor Jolalpa, caught the pizza bug years ago, poking his head into pizza kitchen after pizza kitchen to learn the craft. His leopard-spotted neo-Neapolitan pies look and taste like the stuff of Italian dreams, but are dialed up to 11 with the addition of spicy beef birria and al pastor. 

Chefs Odilon “Odie” Sandoval and Israel Cortez likewise fed their dough obsession at multiple pizza shops before opening a little taqueria and pizzeria called Tonalli on South Philly’s Front Street this summer. 

Sandoval had helped his old friend, chef Eladio Soto, open another restaurant serving Mexican pizza, Point Breeze’s El Mezcal, last year. When Sandoval saw a deck pizza oven in the space that would become Tonalli, it might as well have been fate.

At Tonalli, Sandoval and Cortez don’t just proof their pizza dough overnight, they make two batches in parallel. If they don’t like how one batch of dough has fermented, they don’t use it. 

“We learned from the Italian people,” Sandoval said. “They treat their flour, and they treat their ingredients, with passion.”

The result is crisp and character-filled New York-style dough. The restaurant’s signature pie, borrego en adobo, comes topped with a slow-and-low braised lamb dish called mixiote, seasoned with fire and earthy spice and prepared over the course of two days. On the side is salsa, and a cup of dunkable consome.

“At other pizza restaurants, we were working for other people,” Sandoval said. “Now it is our own. It has to be perfect.”

Valentin Palillero was likely the first to specialize in Mexican pizza in Philadelphia

But Sandoval is careful to give credit to the pioneer of Mexican pizza in Philadelphia. 

Various pizzas with Mexican ingredients have long existed, of course. Pizzerias with Mexican flavors exist in Mexico since at least the 1960s, when Giusseppi’s in Tijuana first served a “Mexicana” pie by adding chorizo and subbing out tomato sauce for refried beans. 

Lettuce-and-ground-beef “taco” pizzas have been around in this country since the 1970s and ‘80s, whether in frozen-food sections or grade-school cafeterias. Though newspaper records are scant on the subject, versions of Mexican-American pies have cropped up here and there but especially in the Southwestern United States, where any food might receive Latin spice — though earlier versions of these pizzas rarely look like Philadelphia’s take, devoted to both the sanctity of Italian crust and the precise fillings you might find in a street taco.

Philadelphia’s Mexican pizza began in Philadelphia, Sandoval said, not in Mexico or elsewhere.  Other local chefs said much the same.

South Philly Mexican restaurants are a small world, one where chefs and owners might have known each other since they were 8 years old — and if not, maybe their mothers are in touch. A large number of local chefs hail from just a couple neighboring towns in Puebla, San Mateo Ozolco and San Lucas Atzala.

Later restaurants may have been more successful in popularizing Mexican pizza here, said Sandoval, a native of San Mateo Ozolco. But the originator of Mexican pizza in Philly is well known to most Mexican chefs in town who serve it.

“The first restaurant who started these Mexicanized Italian pizzas? The first time I tasted carnitas pizza?” Sandoval said. “This is San Lucas Pizzeria.”

San Lucas Atzala is the hometown of chef Valentin Palillero, and it is also the namesake of the pizzeria he and his wife, Eva Mendez, began in 2005.

Palillero’s brainstorm at San Lucas Pizzeria, on South Philly’s McKean Street, came from a simple notion: A pizza slice can be similar to a taco. 

Palillero first learned the craft of pizza dough while working at an Philadelphia airport restaurant in 2000. He honed it at other restaurants thereafter, before opening his own tiny bodega serving both Mexican tacos and Italian-style pizza.

“At first we were trying to sell tacos,” he said. “And we thought, ‘Why not make a pizza, a carnitas pizza?’ You take a small slice, and hmp… taco!” 

He mimes folding a slice of pizza, just as you would a taco. A taco, after all, is a delicious flatbread ― in this case, a corn tortilla ― with the addition of seasoned meats and hot sauce and onions and cilantro. As a pizza chef at other people’s restaurants, Palillero had made himself pizzas with traditional taco fillings as a shift meal.

“My wife always said, if there’s something you make for you, if you like it, maybe customers will like it,” he said.

At first, he said, no one knew what to make of Mexican meats like carnitas or al pastor on a pizza. Not even Mexicans would order them. Italians were even more suspicious. So Palillero began giving out a slice of al pastor or carnitas pizza for free with other orders.

“Then they come in and say, ‘Last time I came, there was a pizza. Can I get one of those?’” Palillero said. 

Eighteen years later, customers are still coming in for his Mexican pizza slices heavy-laden with al pastor, carnitas or chorizo. As word spread over the years, curious people have come in from North Philly, or from as far away as New York or California. Dozens of restaurants around the region liked the idea enough to cook it in their own ovens. 

Still, some question whether Palillero’s take on pizza is actually pizza.

At taqueria and pizza spot El Mezcal, a mile away from San Lucas, there’s a story that a bar manager named Oscar likes to tell. Oscar brims with stories, often about the maker of each bottle of rare mezcal or pechuga on his shelves.

The way this one goes, an Italian-American regular liked to come in for drinks, but refused to try the Mexican pizzas. 

That’s not pizza, the customer said, each time. Finally, his bartender just gave him a slice to try. The customer had to admit that it was delicious. 

It’s good, he said. Maybe just don’t call it a pizza. 

Oscar shrugged, admitting the point.

I get it, he said. A lot of things that you call tacos here, I wish you wouldn’t call them a taco. 

The bartender smiled, and then set a wood-fired chicken mole pizza on the bar counter, smoldering with spice and char.

Matthew Korfhage is a USA Today Network reporter in the broader Philadelphia region, covering culture, food, equity, science and why the trains don’t run on time. Email him at [email protected] or follow him on the site formerly known as Twitter @matthewkorfhage.