Mash black beans with a fork and set aside.
Heat skillet and cook onion, bell pepper, and garlic in small amount of water or oil until soft.
Add mushrooms to skillet and cook.
Add spinach and cook until wilted through.
Add mashed black beans. Stir and cook until heated through.
Spoon filling into warmed tortilla. Top with tomatoes, cilantro, and your favorite salsa. Roll and serve.