Place beans in a 4-quart electric slow cooker. Set aside.
Cut ribs apart; sprinkle with garlic powder, salt, and 1/2 teaspoon pepper. Place ribs on a rack in a broiler pan. Broil 5 1/2 inches from heat (with electric over door partially opened) 18-20 minutes or until well browned, turning once. Add ribs to slow cooker, and sprinkle with onion.
Combine jelly, steak sauce, and if desired, chopped pepper in a sauce-pan; cook over low heat until jelly melts. Pour over ribs; stir gently.
Cover and cook on HIGH 5-6 hours or on LOW 9-10 hours. Remove ribs; skim fat from sauce. Cook sauce with beans, uncovered, on HIGH for 30 minutes or until slightly thickened. Add ribs just before serving to reheat.