01 - Preheat oven to 400°F.
02 - Pat lamb leg dry. Make small, deep incisions all over the meat. Insert garlic slices and rosemary sprigs into each cut.
03 - Rub lamb with olive oil, salt, pepper, chopped rosemary, and thyme, ensuring complete coverage.
04 - Place carrots, onions, and potatoes in a large roasting pan. Position lamb leg on top of vegetables.
05 - Pour wine or broth into pan around the lamb, avoiding the meat surface.
06 - Roast for 20 minutes. Reduce heat to 350°F and continue roasting for 1 hour 15 minutes until internal temperature reaches 135°F for medium-rare.
07 - Remove from oven, tent loosely with foil, and rest for 20 minutes before carving.
08 - Slice lamb and serve with roasted vegetables and pan juices.