01 -
Preheat the oven to 350°F. Spray a 9x13 casserole dish with non-stick cooking spray and set aside.
02 -
Cook ground beef and onion in a large skillet over medium heat until the meat is browned and the onions soften.
03 -
Add minced garlic to the skillet and sauté for 1-2 minutes longer.
04 -
Add taco seasoning and water to the skillet. Stir over medium heat until well combined.
05 -
Stir the fire-roasted diced tomatoes (with juices), green chiles, and black beans into the meat mixture and heat through.
06 -
Line the prepared baking dish with 6 corn tortillas, overlapping slightly to cover the bottom of the dish.
07 -
Spread one-third of the meat mixture over the tortillas. Sprinkle 2 cups of shredded cheese over the meat mixture.
08 -
Repeat the layering process with the remaining tortillas, meat mixture, and cheese to form three layers in total.
09 -
Cover the dish with aluminum foil and bake for 30-40 minutes, or until the casserole is bubbly and the cheese is fully melted.
10 -
Garnish with diced tomatoes and sliced green onions. Allow the casserole to sit for 10 minutes before slicing and serving. Serve with sour cream if desired.