Pour a cup of prepared enchilada sauce into a heat proof measuring cup and add diced onion. Heat in microwave for about 5 minutes to soften.
Cut the tops off of four bell peppers. Remove stems and seeds. Dice the tops of the peppers.
Pour 1/3 c water in the bottom of the crockpot and nestle bell peppers in.
In a large bowl combine one lb uncooked ground beef, onion/enchilada sauce mixture, diced bell peppers, 1 c shredded cheese, 3/4 cup cooked rice, 1 1/2 Tsp salt, 1 Tsp pepper
Fill peppers with ground beef mixture and top with more cheese