A recent discovery of mine has been THE TORTA. It's a Mexican sandwich, kind of like a burrito on a roll. The meat inside is up to you; it's the other stuff that gives it the unique Mexican identity. I recommend something slow cooked, like roasted pork or perhaps some leftover chicken, shredded and heated up in a pan. One of my favorite breakfast sandwiches ever has chorizo and egg scrambled together and put into a torta.
--Beans (Refried, Black Beans, or Pinto Beans)
--Sliced Fresh Avocado
--A slice of White Cheese (Queso Blanco)
--Slice of Tomato
Toast a roll. On the top bun, place the lettuce, a slice of tomato, sliced avocado and a slice of white cheese. On the bottom bun, spread beans, then lay a couple of slices of pickled jalapeno. Place your meat on top of that, then close the sandwich. Oh, I've also see recipes that include Sliced Onion, Sour Cream, and Mayonnaise. Really, it's your call!