1. In a 3-1/2- to 4-quart slow cooker place the potatoes, sweet pepper, and onion. Sprinkle tapioca over potato mixture. Place chicken on top of the vegetables. For sauce, in a small bowl stir together tomato sauce, brown sugar, Worcestershire sauce, mustard, garlic, and salt. Pour sauce over chicken.
2. Cover; cook on low-heat setting for 10 to 12 hours or on high-heat setting for 5 to 6 hours.
3. Transfer chicken and vegetables to a large serving bowl. Skim fat from sauce. Spoon sauce over chicken and vegetables. Makes 4 to 5 servings.