In a large skillet, heat the butter or oil over medium heat. Add the chopped onion and bell pepper, sautéing until they are soft and fragrant, about 3-4 minutes.
Add the black beans, corn, cilantro, lime juice, and all the spices (paprika, garlic powder, onion powder, cumin, salt, and black pepper) to the skillet. Stir well to combine and cook for an additional 2-3 minutes until heated through.
If using, stir in the cooked rice until fully mixed. Then, sprinkle in the shredded cheese, allowing it to melt and bind the filling together.
Lay a tortilla flat on a clean surface. Spoon 1/8 of the filling into the center of the tortilla. Fold in the sides and roll tightly from the bottom to the top. Repeat with the remaining tortillas and filling.
In the same skillet, add a little oil or cooking spray over medium heat. Place the burritos seam-side down in the skillet. Cook for 3-4 minutes on each side until golden brown and crispy. You may need to work in batches to avoid overcrowding the pan.
Once crispy, remove the burritos from the skillet and let them cool slightly. Serve warm with your favorite dipping sauces, like salsa or guacamole.