Sear the lamb first, on both sides, grilling on high heat for a short amount of time. Then cook the lamb on lower heat until it is cooked through. In my opinion, the only way to eat lamb is medium rare or rare. There is nothing more depressing than dried-out, over-cooked lamb! For this reason it is essential that you use a meat thermometer to test the internal temperature of the roast. Preparation time DOES NOT include the 2 hour marinating time in the refrigerator!