Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, bell peppers, onion, black beans, diced tomatoes, corn, sour cream, taco seasoning, garlic powder, cumin, salt, and pepper. Mix well until all ingredients are evenly coated.
In a greased 9x13 inch baking dish, layer half of the tortilla strips on the bottom.
Spread half of the chicken mixture over the tortilla layer.
Sprinkle half of the shredded cheddar cheese on top of the chicken mixture.
Repeat the layers with the remaining tortilla strips, chicken mixture, and finish with the remaining cheese on top.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.
Let the casserole cool for 5-10 minutes before serving. Garnish with fresh cilantro, if desired.