Boned leg of lamb will probably be a rather compact piece of meat with large pocket. With sharp knife, cut down through thinnest side of pocket and spread leg flat, fat side down, in large shallow baking dish.
Mix oil, grapefruit concentrate, salt, pepper, parsley, rosemary and bay leaves. Add onion and garlic. Pour marinade over meat, cover and refrigerate 24 hours, turning every few hours. Remove from refrigerator and allow to sit at room temperature before broiling.
Remove from marinade, reserving marinade; sprinkle both sides with coarse salt and place on grill about 5-6 from heat. Cook 45 minutes, turning occasionally and basting with marinade. Cut against grain into 1/4 inch slices.Servings: