1.Preheat oven to 350°F Roast Mode with a rack at position “3."
2. Pat lamb dry with paper towels. Using a sharp knife, score the fatty side of the lamb, making shallow cuts all over. Place lamb fatty side up on a rack in a roasting pan.
3. In a small bowl, combine garlic, olive oil, rosemary, thyme, Dijon mustard, salt, and pepper. Spread mixture evenly over lamb, thoroughly rubbing into scored cuts.
4. Using the temperature probe, roast until lamb reaches an internal temperature of 135°F for medium doneness, about 1 hour 30 minutes, or until desired doneness.
5. Rest 15 minutes before slicing.