In a large skillet, cook beef, green pepper and onion until meat is no longer pink; drain. Add water and taco seasoning - bring to a boil. Reduce heat and simmer uncovered for 3-4 minutes. Stir in black beans and tomatoes. Simmer uncovered for 10 minutes.
Place 2 tortillas in a greased 13x9x2-inch baking dish. Spread half of the beans on top of the tortillas. Top with half of the beef mixture. Sprinkle with 1 cup of cheese. Repeat layers. Top with remaining tortillas and cheese. Cover and bake at 350° F. for 30 minutes or until heated through and cheese is melted. Let stand 5-10 minutes before cutting.
Notes
Use plain diced tomatoes if the ones with peppers are too spicy for your family.