Preheat the oven to 350 degrees
Saute the onion in 1 Tbsp. of olive oil until tender
Grease a 9x13 pan and add 1/2 cup of the sauce
Top the sauce with 6 corn tortillas
Sprinkle 1/3 of your chicken over the tortillas
Follow that with 1/3 of the onion, 1/3 of the black beans, 1/3 of the chilies, and 1/3 of the cheese
To that, add another layer of corn tortillas and everything that you added the first layer
Do this one more time ending with the cheese
You may have a little bit of extra sauce. You can leave it out, or pour on to the top
Bake for about 20-30 minutes
While that is baking Mix the Guacamole ingredients together in a food processor - or if you prefer, stir and mash with a fork in a small bowl
Also, cube the remaining avocado and tomatoes to serve with the lasagna. Add chopped cilantro to this and stir in
Top lasagna with fresh avocado and tomato mixture
Serve with Guacamole and Sour Cream