Chilorio was originally a preservation method, cooking pork slowly in lard and chile until it could keep for days without refrigeration — long before it became a taco and burrito filling.
Pork is simmered until tender, shredded, then fried with a paste of dried guajillo and ancho chiles, garlic, and vinegar until deeply red and slightly crisp at the edges. Market stalls across Sinaloa spoon it into tacos, burritos, or tortas.