Pour 1/2 cup of enchilada sauce into the bottom of a 9x13 pan and spread over the bottom in an even layer. Set aside the remainder of the sauce.
In a large skillet over medium heat, heat the oil. Add the onion and cook for 5 minutes, then add in the red pepper. Cook until both are soft, then add in the garlic and cook until fragrant.
Stir in the black beans, corn, chicken, and green chilis. Saute for 4-5 minutes, until the ingredients are hot.
Pour in the remaining enchilada sauce and stir to coat everything.
Place 6 tortillas on top of the enchilada sauce in the pan, overlapping them to cover the bottom completely.
Spread out 1/3 of the hot bean mixture on top of the tortillas.
Spinkle one cup of Monterey Jack on top, followed by 1/2 cup shredded cheddar.
Top with another layer of tortillas and repeat, making two more layers of tortillas/mixture/cheese, finishing with a layer of cheese on top.
Bake in the preheated oven for 30-35 minutes, until the sauce is bubbling through the top in places and the cheese has melted. If needed, cover the top lightly with foil to prevent the cheese from browning too much.
Garnish with the avocado,sour cream and cilantro, then slice like a lasagna and serve.