2 kg lamb leg bone in
Sea-salt flakes and freshly ground black pepper, to season
4 tbsp extra virgin olive oil
2 bunches rosemary
4 whole bulbs garlic
4 medium sweet potato
20 g butter, chopped
200 ml white wine
1 tbsp cornflour
60 ml cold water
- Preheat oven to 200°C. Season lamb with salt and pepper. Drizzle with ½ the oil and rub all over.
- Lay rosemary in a large roasting dish. Sit lamb on top. Arrange garlic next to lamb.
- Rub sweet potato with remaining oil and arrange next to lamb.
- Roast for 1 hour, then remove sweet potato and set aside to cool. Roast lamb and garlic for a further 30 minutes for medium or until cooked to your liking. Rest for 30 minutes.
- When cool enough to handle, peel off skins from sweet potato. Put flesh in a large bowl with butter, and season. Mash until smooth. Cover with foil to keep warm and set aside.
- Pour pan juices into a small saucepan. Squeeze in flesh of 1 bulb of garlic. Add wine and bring to a simmer. Combine cornflour with water until a smooth paste forms. Add to pan. Stir well to combine. Bring to a simmer and stir until thickened and smooth.
- Serve lamb with sweet potato mash, extra roasted garlic and gravy on the side.