Boneless loins are sold with the silver skin removed. If you happen to have some with this skin on, merely trim off with a sharp knife before marinating. To grill only 4 loins for fewer people, reduce the marinade ingredients by half. Hoisin sauce and rice vinegar are available in most supermarkets, or speciality shops. Prep. time includes marinating time in refrigerator. Calculate less time if marinating at room temperature. Cook-time includes stand-time. Serve with grilled vegetables and a plain salad with balsamic vinegar and extra-virgin olive oil dressing. Makes a welcome barbeque supper.