Saute in oil; mushrooms, onion, pepper, garlic salt and pepper. Cook ujntil onion is transparent. Add spinach, cook until spinach just begins to wilt. Stir in cilantro and remove from heat. Place 1/4 veggie mixture on half of tortilla. Sprinkle with 1/4 of cheese. fold tortilla in half to cover mixutre. Place tortillas on ungreased cookie sheet. Broil in oven 2 minutes, flip and broil 2 more minutes. Top with salsa & sour cream if desired.