– 1 1/2 lb flank steak sliced into thin slices about 1/2 inch long – 2 tablespoons avocado oil – 1 tablespoon Montreal Steak Seasoning or to taste – 8 slices American white cheese – 1/2 cup pepper jack cheese grated, or use any cheese of your choice – 6 raw or cooked tortillas – 1 tablespoon butter melted – salsa, sour cream & cilantro for serving