Cut lamb into 2, 4-rib racks. Trim excess fat and place in sided dish just large enough to hold them. Mix together marinade and pour over lamb. Coat lamb on both sides with marinade. Cover and marinate in fridge 4 hours or overnight, turning lamb over occasionally. Preheat oven to 425 degrees F. Place lamb in roasting pan. Brush on marinade. Roast 22-25 minutes for rare, 25-28 for medium rare, and 30 for medium. Baste with pan juices a few times during cooking. Rest the lamb 5 minutes to allow juices to set before serving. If you would like to make jus to serve with the lamb, remove fat from the pan, add 1 cup of beef stock, simmer a few minutes, and then season with salt and pepper.