Preheat the oven to 375°F.

Cook your ground beef in a medium skillet over medium-high heat for about 5 minutes, or until it is no longer pink in the middle. Use a spatula to break up the beef while it cooks and drain as much grease as you can once it is fully cooked.

Add the taco seasoning, green chilis, and black beans to the pan. Reduce the heat to low and slowly stir the ingredients together, letting the mixture continue cooking for 3-4 more minutes. Set aside.

Add a few spoonfuls of salsa to the bottom of a 9x13 inch baking pan. Place 2 whole tortillas on the bottom of your pan and then cut 2 additional tortillas to fill the gaps. Top your tortillas with sour cream followed by salsa, half of the beef mixture and 1 cup of cheese.

Repeat this process again. Top the second layer of beef with the remaining tortillas, a few more spoonfuls of salsa, and the remaining cheese.

Bake the casserole for 30 minutes, or until the cheese is melted and bubbly.

Let the taco lasagna rest on the counter for about 5 minutes before slicing. Serve and enjoy topped with shredded lettuce and additional salsa, if desired.