Preheat the oven to 200C.
Make sure the lamb has come up to room temperature before cooking.
Place the lamb shoulder into a roasting tin. Rub the skin all over with olive oil and then cut some incisions into the skin and insert some peeled garlic cloves and small sprigs of rosemary into the cuts. Season generously with cracked black pepper and Maldon salt.
Place the lamb into the hot oven and roast for 30 minutes until the skin has browned and crisped up. Then remove from the oven and turn the oven temperature down to 150C. Carefully pour the stock into the tin around the lamb and add the wedges of red onion and lemon around the lamb. Cover the tin with tin foil and seal the edges.
Place the lamb back into the oven and allow it to cook for 4 – 5 hours. After it has had this time the lamb should be meltingly soft and tender and pull away from the bone easily. Use the lamb cooking juices to make a gravy and serve alongside the rest of your Easter table sides; roasted carrots with thyme, minted new potatoes, steamed greens and mint sauce.