Cook rice. Cut off top of peppers then hollow out. Steam green peppers until slightly tender. Brown ground beef. Add rice, tomato sauce, water, onion, salt, pepper. Simmer. Drain peppers. Add salt. Fill peppers with meat/rice mixture. Top with one heaping tablespoon cheese. Top with a sliced mushroom. Heat until cheese melts. Can be frozen, then warmed in microwave oven.