Boil the potatoes in plenty of salted water. Once cooked, peel and cut them into cubes.

Meanwhile, remove the stems and seeds from the chiles and boil them for 10 minutes. Blend the chiles with the piece of onion, garlic, and salt. Heat the sauce, add the chile cooking water, and season with salt. The sauce should be thick and not too salty.

Cook the chorizo in a skillet. Once cooked, add finely chopped onion, stir, and cook for 15 minutes.

Slice the rolls in half. Using a brush, spread the chile sauce on both sides and heat them on a griddle or skillet. Fill with the chorizo and potato mixture.

Serve topped with crema, lettuce, Cotija cheese, green salsa, and onion to taste.