Combine soy sauce, tomato paste, hoisin, sherry, sugar, ketchup, grapefruit juice, honey and crushed garlic cloves in a non metallic bowl. Mix thoroughly. (Before adding the ribs, peel the membrane off the back of the ribs. This will make them wonderfully tender). Pour marinade into the bag, add ribs and marinate for 2 hours turning occasionally. Grill 40 minutes basting with leftover sauce once in the first 30 minutes of grilling. Throw out the rest of the marinade that is not used.