In a small saute pan, set to medium heat and spray with cooking spray. Add black beans, peppers, mushrooms and spinach, cook for about 3-5 minutes.
In a larger skillet, lay the tortilla flat and cover one half with 1 Tbsp. cheese. Top half with vegetable mixture. Then cover with remaining cheese and fold tortilla. Flip after about 2 minutes. (Do not put oil or butter on tortilla, this should toast dry.)
Slice in half. Serve with salsa, avocado and sour cream, if desired.
Source: Brandi Koskie