To make guajillo sauce, you’ll need guajillo chile, chile de arbol, garlic, onion, oregano, thyme, salt, and pepper. However, these chiles are sold dried, so you won’t find them at the produce counter. Look for dark red dried peppers. Large peppers are for guajillo, small, thin ones are for arbol. The chile de arbol can be swapped out or omitted, but I don’t recommend omitting the guajillo chile.
For the sandwich filling, you will need a large eggplant, flour, eggs, breadcrumbs, oil for frying, shredded lettuce, sour cream (or crema), cotija cheese, and ripe avocado. Of course, the most important ingredient is bread. Bread should be tested and sourced a few days before cooking. For that, look for a telera roll or bolillo roll, which are dense rolls that resemble giant hamburger buns. If you can’t find these, use hamburger buns to make small pamberzos.