Preheat oven to 350 F. Heat up olive oil in a skillet over medium heat. Stir in bell pepper and onion. Cook for about 5, until onion becomes translucent.
Add the mushrooms. Reduce heat to low. Cook for 8-10 minutes, until the mushrooms are soft and blackened. Add a dash of salt and pepper to taste. Stir in Mexican cooked rice (optional) and about 2 tablespoons of green enchilada sauce. Remove from heat.
Add a layer of non-stick spray with a thin layer of enchilada sauce to baking dish. Assemble enchiladas with tortillas and roasted filling, taquito-style. Pour remaining enchilada sauce and top with cheese. TIP: To prevent the tortillas from breaking upon assembly, heat them in a small pan over medium heat with thin amount of oil. This will soften them and give a richer flavor too.
Cover dish with aluminum foil and place in oven for 15 minutes. Serve immediately with cilantro, guacamole, lime, or any desired toppings.