01 - Preheat oven to 375°F. Lightly grease a 9x13-inch casserole dish with nonstick spray or butter.
02 - Heat a large skillet over medium heat. Sauté the diced onion, red bell pepper, and minced garlic for 3 to 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 to 3 minutes until heated through.
04 - Spread a thin, even layer of salsa across the bottom of the prepared casserole dish. Arrange 3 tortillas over the salsa, tearing as needed to create an even coverage.
05 - 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.
06 - Repeat the layering: arrange the remaining 3 tortillas, spread the rest of the chicken mixture, pour the remaining enchilada sauce and salsa, and top with the final cup of shredded cheese.
07 - Cover the casserole tightly with aluminum foil and bake for 20 minutes to allow the layers to heat through and meld together.
08 - Remove the foil and continue baking for 10 minutes until the cheese is bubbly and lightly golden on top.
09 - Remove from the oven and let the casserole rest for 5 minutes. Dollop with sour cream and sprinkle with fresh cilantro before serving.