Felicity Cloake’s ” Perfect” version.
Rub the meat with oil. Sprinkle over the cinnamon, oregano and salt, and peel and roughly crush half a head of garlic. Rub all this into the meat with your hands along with the juice of one lemon. Cover and leave for 12 hours.
Heat the oven to 160C. Cut the potatoes into wedges and use them to line the base of a large lidded casserole dish (or use a roasting tin lined with enough parchment paper to fold over the top of the joint on both sides – you’ll probably need two pieces at right angles). Cut the onion into wedges and the pepper into chunky strips, removing the seeds, then add the cherry tomatoes.
Place the lamb on top. Cut the remaining garlic and lemon in half laterally, squeeze the lemon briefly over the potatoes, and tuck the shells and the garlic in around the joint along with the bay leaf. Pour 200ml water into the dish. If using a casserole dish, tuck a damp piece of greaseproof on top and cover, if using a roasting dish, sprinkle the overhanging paper with water and fold over and tuck in to form a sealed package. Bake for 4-5 hours until very tender.
Turn the oven up to 220C and roast, uncovered, for 10-15 minutes at this higher temperature, then lift the joint out and set aside. Put the vegetables back in for 15 minutes until starting to brown, then serve with the meat.