Preheat oven to 350 degrees F. Lightly grease a 9-inch pie dish.
In a large bowl, combine the chicken soup, diced tomatoes with green chilies, black beans, green bell pepper, taco seasoning and chicken. Set aside.
Tear 5 corn tortillas and line them on the bottom of the pie dish.
Spread half of the chicken mixture over the tortillas. Top with ¾ cup of cheese.
Tear remaining 5 corn tortillas and place on top. Add remaining filling, then top with remaining cheese.
Bake for 30 minutes or until cheese is bubbly and mixture is warmed through. Serve topped with sour cream, chopped cilantro and avocado.
