Roast leg of lamb with caper & lemon butter crust

1. Preheat the oven to 220°C, gas mark 7. Season and toss the potatoes, celeriac and onion over the base of a large roasting tin; pour over 100ml water. Use a pestle and mortar to crush the garlic, rosemary, juniper and capers to a rough paste; stir in the butter with the lemon zest and plenty of black pepper.

2. Pierce the lamb all over with a sharp knife and rub with the butter mixture. Sit the lamb on top of the potatoes, season with sea salt and roast for 20 minutes. Reduce the heat to 180°C, gas mark 4, and cook for 1 hour 20 minutes, rotating the lamb halfway. Lift the lamb off the potatoes and rest on a board loosely covered with foil.

3. Increase the heat to 200°C, gas mark 6. Tip the tin and baste the potatoes with any juices; return to the oven for 30 minutes while the lamb rests. Before serving, pour off and discard any excess fat from the potatoes. Serve with the sliced lamb, gravy and steamed greens, if liked. 

Cook’s tip
You can vary the aromatics in the butter crust. Try sage or thyme instead of rosemary, anchovies instead of capers or fennel seeds instead of juniper berries