1. Heat the oven to 400°F.
2. Cook the beef in a 10-inch skillet over medium-high heat until well browned, stirring often to separate meat. Pour off any fat.
3. Stir the soup, salsa, water, tortillas and half the cheese in the skillet. Pour the beef mixture into a 2-quart shallow baking dish. Cover the baking dish.
4. Bake for 30 minutes or until the mixture is hot and bubbling. Sprinkle with the remaining cheese.