I like to use McCormick's spices of Garlic and Herb to marinate chicken breast (boneless; strips or breast. I mainly use strips as it's easier to dice up. If it gets flakey, don't panic, use it! It doesn't have to be perfect) with EVOO, S&P for 30 minutes or more until you are ready to cook. I cooked the chicken for about 7 minutes or so before I take it out to let it rest while I clean out the same pan to heat up the buttered-tortillas
I also used Sargento's 5 Mexican cheeses (or Cheddar/Montery Jack)
Also: either scallions, cilantro, or caramelized onions to go inside with the chicken and cheeses.
I used my grill-saute cooking pan to make those lovely grill marks.
Served with a couple of dollops or sour cream. Or Salsa.
If you are a vegetarian, just leave out the chicken.