Preheat oven to 350 degrees. Spray a 9×9 baking dish with non-stick spray.
Add the beef to a large skillet over medium heat and crumble as it cooks. Drain grease when cooked through.
Add the taco seasoning and water to the skillet and cook for 2 minutes.
Dump the tomatoes, cheese soup, and sour cream into a medium mixing bowl. Stir in the cooked meat.
Place 3 tortillas in the bottom of the prepared baking dish. Top with 1/3 of the meat mixture.
Repeat layers, ending with a layer of tortillas on the top. Sprinkle the cheese over the top.
Bake for 20 minutes or until hot and melty.
Serve sprinkled with chopped cilantro, guacamole, and extra sour cream, as desired.
