Trim lamb of fat. Cut slits about 1/2 inch deep all over lamb and insert slivers of garlic. Rub all over with olive oil. Combine salt, pepper, and herbs and rub herb mixture all over lamb. Allow to sit at room temperature 20 minutes.
Preheat oven to 450 degrees. Roast lamb for 15 minutes at 450 degrees, then turn oven down to 350. Continue to roast until desired degree of doneness is reached, about an hour for medium rare. Baste with pan juices once or twice. Remove from pan and allow to rest at room temperature for 15-20 minutes before carving.
Potatoes, carrots, and onions may be roasted in pan with lamb. Baste occasionally.