Ingredients

Step by step

1. Remove the lamb from the fridge and unwrap 30 minutes before roasting. Place in a large roasting tin and pat dry with kitchen paper. Preheat the oven to 190°C, fan 170°C, gas 5.
2. Rub the olive oil over the joint and season with salt and freshly ground black pepper. Use the tip of a sharp knife to make 7-8 deep cuts into the lamb. Spoon a little of the mint sauce into each cut. Roast for 1 hour.
3. Remove the roasting tin from the oven and spread 2 tablespoons of the remaining mint sauce all over the joint. Roast the lamb for a further 40 minutes, covering the joint loosely with foil to prevent overbrowning after 20 minutes. Add the onion slices to the tin, turning to coat in the meat juices in the base of the pan. Roast for another 20-30 minutes or until the lamb is cooked to your liking and the onions are just tender.
4. Transfer the lamb to a warmed serving platter, cover with foil and leave to rest for 30 minutes. Keep the onions warm in a low oven. Serve the lamb and onions with the rest of the mint sauce and with roast potatoes and steamed green beans, if liked.