In a large skillet, cook beef and onion until the meat is no longer pink; drain. Add the beans, chili powder, cumin and salt. , Transfer to a greased 13x9-in. baking dish. Arrange tortillas over the top. Combine soup and tomatoes; pour over tortillas. Sprinkle with cheese. , Bake, uncovered, at 350° for 25-30 minutes or until heated through.