Combine first 6 ingredients and salt and pepper to taste in a bowl. Place lamb in a plastic bag and pour marinade over. Seal tightly and marinate in refrigerator several hours or overnight. Preheat oven to 325°F. Place lamb on a rack in a baking pan, reserving marinade. Bake 20-25 minutes per pound, brushing occasionally with marinade, until a meat thermometer registers 145°F for medium rare. Remove from oven, cover lightly and let stand 15 minutes before slicing.
