01 - Preheat oven to 400°F.
02 - Using a sharp knife, make small incisions all over the lamb. Insert a garlic slice into each incision.
03 - In a small bowl, combine olive oil, rosemary, thyme, salt, and pepper. Mix thoroughly.
04 - Rub the herb mixture evenly over the entire surface of the lamb, pressing gently to adhere.
05 - Place lamb on a rack in a roasting pan. Roast for 1 hour 30 minutes for medium-rare (internal temperature 140°F), basting with pan juices once or twice during cooking.
06 - Combine chopped mint and sugar in a heatproof bowl. Pour boiling water over the mixture, stir, and let stand for 5 minutes. Stir in vinegar and pinch of salt. Adjust seasoning to taste.
07 - Transfer cooked lamb to a carving board. Cover loosely with aluminum foil and let rest for 15 minutes before carving.
08 - Carve lamb into slices and serve with mint sauce and roasted vegetables on the side.