Preheat oven to 350 degrees F. Line a roasting pan with aluminum foil.
Pat lamb dry with paper towels. Using a sharp knife, score the top side of the lamb with shallow cuts.
In a small bowl, mix garlic, olive oil, rosemary, thyme, Dijon, salt and pepper.
Place lamb, on a rack in the prepared roasting pan. Spread garlic mixture evenly over the lamb.
Place into oven and roast until it reaches an internal temperature of 135 degrees F for medium, about 1 hour 30 minutes to 1 hour 45 minutes, or until desired doneness. Let rest 15 minutes before slicing.
Serve immediately with potatoes.
