Preheat the oven or a charcoal barbecue to 190°C. If oven-roasting the lamb, place it in a small roasting pan in the middle of the oven. If using the barbecue, make sure the coals are glowing and place the meat directly onto the grill. Roast for about 70 minutes. Test with a skewer to ensure the juices are almost clear. Once the meat is cooked but still juicy, remove from the heat, cover with foil and leave to rest for about 15 minutes.