John Whaite's slow-cooked roast lamb

John Whaite cooks up his delicious, hassle-free slow-roasted lamb.

Easily serves 6-8Prep: 20 minutes, plus marinating timeCook: 5½ hours

Ingredients:100g jar anchovies in olive oil8 garlic cloves1 tbsp mint sauce2kg leg of lamb6 medium Maris Piper potatoes Sea salt flakes Coarse black pepper

Method:

• Make a marinade for the lamb by blitzing the anchovies and the oil they came in, with the peeled garlic cloves and the mint sauce to a smooth paste in a food processor. If you do not have a food processor you could make the paste by finely chopping the anchovies, and mixing with crushed garlic and mint sauce. Stir in 1 teaspoon each of salt and pepper.

• With a sharp knife, pierce the lamb leg repeatedly all over – you need as many deep cuts as possible, without completely massacring the meat. Spread the paste over the entire surface of the meat, working it well into the cuts. Refrigerate for an hour, or until required.

• Preheat the oven to 160°C/140°C fan/gas mark 3 and remove the lamb from the fridge 1 hour before it goes into the oven to bring it up to room temperature.

• Slice the unpeeled potatoes as neatly as possible – (a mandolin is good for this)– and arrange them in layers in a deep-sided roasting dish, seasoning with a very small pinch of salt and pepper every couple of layers. Place the lamb on top of the potato slices. Cover with a couple of sheets of foil, ensuring you seal it extremely well. Roast in the oven for 4 ½ hours.

• Remove the tray from the oven and increase the heat to 220°C/200°C fan/gas mark 7. Remove the foil and baste the lamb with some of the juices from the roasting tin. Put everything back into the oven for a further 30 minutes. Remove the lamb from the oven, transfer it to a plate, cover it with foil and leave to rest. Return the potatoes to the oven for a further 25–30 minutes, until slightly crispy around the edges.

Serve with honey glazed carrots and seasonal vegetables of your choice.