Crisp is the entire argument of the taco de tripas. The filling is beef small intestine, cleaned thoroughly and then cooked on the griddle until the outside crackles and the inside keeps a yielding, fatty chew. That chewy-crispy duality is what defines the taco, and the warm corn tortilla is its necessary partner. The tripas bring a deep, rendered-fat savor and a texture that goes from shatter to give in a single bite; the tortilla brings a toasted corn base that catches the fat and gives the small, slippery pieces something to sit on. They depend on each other in the plainest way. Tripas eaten loose are a greasy handful with nowhere to go, and a bare tortilla is just bread, but folded together the tortilla absorbs the rendered fat while the intestine carries the flavor.
The whole craft lives at the griddle. The tripas have to be cleaned without mercy, then cooked low until the fat renders and the tissue softens, then pushed hard against the hot steel so the exterior crisps into something close to crackling while the center stays tender. Rush that final sear and the result is rubbery; over-render it and there is nothing left but a chew. The tortilla is warmed on the comal until it flexes, then filled with a moderate scoop of chopped tripas lifted straight off the heat so the crisp is still alive. Onion and cilantro add bite, lime cuts the richness, and a forceful salsa, often a chile de árbol or a roasted salsa verde, stands up to the fat without overwhelming it. The careful builder keeps the portion honest, the pieces freshly crisped, and the fold tight so the taco eats clean and the crackle survives to the last bite rather than steaming soft under a wet pile.
Use the milk-fed calf cut instead and the taco turns pale, mild, and almost creamy, a far gentler thing that deserves its own article rather than being crowded in here. Braise the tripas soft in a stew and skip the crisp entirely and you reach the guisado version, a different texture and intent that deserves its own article rather than being crowded in here. Wrap crisped tripas in a flour tortilla with melted cheese on the griddle and you have moved into a northern tripa fold that deserves its own article rather than being crowded in here.