Combine hoisin sauce, soy sauce, green onions and garlic powder; pour over ribs in large plastic food storage bag. Press air out of bag; close top securely. Turn bag over several times to coat both sides of ribs. Refrigerate 1 hour; turn bag over and refrigerate 1 hour longer. Grill ribs over medium-hot fire 45 to 60 minutes or until done, turning ribs over occasionally. (Or bake ribs, meaty side up, in large, shallow foil-lined baking pan in 325°F oven 1 ½ to 2 hours, or until done, turning over every 30 minutes.)