Add an equal amount of sliced bell pepper to the onion and I am big fan of this method. Replace the Adolph's with cumin. Also add a side of sour cream to the guac and salsa condiments (if you aren't averse to dairy). I do the same with thin pork chops and pounded/flattened chicken breasts. Primal tortillas need to be perfected. Anybody? Flap steaks are an excellent replacement for skirt.