The best temperature for grilling lamb is medium-high heat, typically around 375°F to 450°F (190°C to 230°C). This temperature allows the lamb to cook evenly and develop a flavorful crust on the outside while maintaining juiciness on the inside. It's important to preheat the grill to this temperature before placing the lamb on the grates. This ensures that the lamb sears properly and locks in the juices, resulting in a delicious and tender grilled leg of lamb. Remember to use a meat thermometer to check the internal temperature and achieve the desired doneness.