Place lamb in a shallow bowl and pour marinade over. Cover with plastic wrap and marinate for 2-3 hours or overnight, turning the lamb from time to time.
Set up a covered gas or charcoal grill for indirect cooking. Remove lamb from marinade and discard marinade. Cook lamb for 45 minutes or until the internal temperature reaches 125-130°F in the thickest part for medium-rare. Thinner parts will be more done. Remove from grill and let lamb rest for 10-15 minutes loosely covered with foil.
