Combine all marinade ingredients in a small bowl. Rub marinade over lamb. Cover and refrigerate overnight. When ready to cook, remove lamb from the refrigerator and let rest on the counter while you preheat the oven to 375°.

Place a rack inside a roasting pan and place the lamb on the rack. Slide the roasting pan into the preheated oven. Roast until a meat thermometer reads 120°. Pull the roasting pan from the oven and place an aluminum foil tent over the lamb. As the lamb rests, it will continue to cook from the internal, residual heat. A temperature of 125° is medium rare, 130 is medium, 140 is medium well, and 150 is well done.