1. Pierce Lamb and insert spears of garlic
2. Mash herbs, salt and pepper and butter together using your hands and coat the lamb.
3. Place it into your cast iron pot and cook at 120° for 3 hrs with the lid in.
4. Remove the lid and put under a grill on high for 3-5 minutes or until brown. This gives it a beautiful crisp skin without heating it to the point of damaging the fats
5. Leave to rest for 10 minutes and then serve