Try this on the grill, it's awesome! (heat the grill to high, sear the lamb for about 5 minutes on all sides, reduce the grill heat to medium and cook for about 30 minutes for med-rare). Plan ahead the lamb needs to marinade for 24 hours. Since the lamb is butterflied you will need a large baking pan to cook in the oven, to save time as your butcher to butterfly it for you.