Chili Bean-Stuffed Peppers

Remove tops, membranes, and seeds from sweet peppers. Chop enough tops to make 1/3 cup; set aside. If necessary, cut a thin slice from the bottom of each pepper so they sit flat. In a medium bowl stir together rice and undrained beans; spoon into peppers. Pour tomato sauce into the bottom of a 4 1/2-, 5- or 6-quart slow cooker; stir in reserved chopped pepper and onion. Place peppers, filled side up, in cooker. 

Cover and cook on low-heat setting for 6 to 6 1/2 hours or on high-heat setting for 3 to 3 1/2 hours.