Tlayuda con Chorizo Oaxaqueño y Quesillo

This is Oaxaca's tlayuda. It comes from the Valles Centrales, the broad highland valleys around the city of Oaxaca de Juárez, and specifically from the market stalls and street corners where women have been building them over charcoal for longer than anyone can remember. If someone calls it a "Mexican pizza," leave the conversation. A pizza is bread with toppings. A tlayuda is a dried corn tortilla the size of a steering wheel, spread with asiento and black beans, loaded with whatever the cook decides you need, and grilled until the edges char and the quesillo pulls into long strings. The two have nothing in common.

The ingredient that separates a tlayuda from a big tostada is asiento. Asiento is the dark, thick sediment left at the bottom of the cazo after frying chicharrón: concentrated pork flavor, slightly bitter, deeply smoky, with a texture somewhere between soft lard and a coarse paste. The senoras at the Mercado 20 de Noviembre spread it across the tortilla with the back of a spoon before anything else goes on. Without asiento, you don't have a tlayuda. You have a big crispy tortilla with things on top. La manteca es el sabor, and asiento is manteca in its most concentrated, most Oaxacan form.

The chorizo on this version is oaxaqueño, and that matters. Chorizo oaxaqueño is not the sweet, paprika-red sausage you find in Toluca or the smoky links from Monterrey. It's vinegar-tart, made with chile ancho and sometimes pasilla oaxaqueño, with a sharp acidity that cuts through the richness of the asiento and the fat of the quesillo. You crumble it into a dry skillet and it renders its own orange-red fat, tinting the pan. When it hits the beans and the melted cheese on the tortilla, the whole thing comes together: smoky, tart, rich, crisp at the edges.

I ate my first proper tlayuda in the 20 de Noviembre market at eleven o'clock at night, standing at a metal counter while a woman worked four of them at once over a charcoal grill. She didn't ask what I wanted on mine. She built it, folded it in half, and handed it to me wrapped in brown paper. I wrote "asiento" in my notebook and underlined it three times. Cada estado, su propia cocina, and this one belongs to Oaxaca.