1. In a large skillet, cook beef, green pepper and onion over medium heat until meat is browned; drain fat. Add water and taco seasoning; bring to boil. Reduce heat and simmer, uncovered for 2 minutes. Stir in black beans and tomatoes.simmer, uncovered for 10 mins.
2. Place two crispy corn tortillas in greased 13x9" baking fish or a 2 1/2 qt. casserole and smaller casserole. Spread with half refried beans and beef mixture; sprinkle with one cup cheese. Repeat layers. Top with soft tortillas and cheese.
3. Cover and bake at 350 degrees for 25 to 30 mins. until heated through and cheese is melted.