01 - Preheat oven to 375°F. Lightly grease a 9x13-inch casserole dish with nonstick spray or butter.
02 - In a large skillet over medium heat, sauté the diced onion, red bell pepper, and minced garlic for 3-4 minutes until softened and fragrant.
03 - Add the shredded chicken, drained black beans, cooked rice, chili powder, cumin, salt, and black pepper to the skillet. Stir thoroughly to combine and cook for 2-3 minutes until heated through.
04 - Spread a thin, even layer of salsa across the bottom of the prepared casserole dish.
05 - Place 3 tortillas over the salsa layer, tearing them as needed to create full coverage.
06 - Spoon half of the chicken and bean mixture evenly over the tortillas. Drizzle with half of the enchilada sauce and half of the remaining salsa. Sprinkle 1 cup of shredded cheese on top.
07 - Repeat the layering: arrange the remaining 3 tortillas, spread the rest of the chicken mixture, drizzle the remaining enchilada sauce and salsa, and top with the final cup of shredded cheese.
08 - Cover the casserole dish tightly with aluminum foil and bake for 20 minutes to allow the layers to meld and heat through.
09 - Remove the foil and continue baking for 10 more minutes until the cheese is bubbly and lightly golden on top.
10 - Remove from the oven and let the casserole rest for 5 minutes before slicing. Dollop with sour cream and sprinkle with fresh cilantro before serving.