Lancashire hotpot

Lamb and onions baked slowly under a lid of overlapping potato slices. The potatoes on the bottom of the layer melt into the juices and thicken them, so there's no need for flour. The top layer, brushed with tallow, goes crisp and golden.

• Serves 6, deep 3 litre lidded casserole
• Active 40 min
• Total about 3½ hours

Ingredients

• 1.2 kg lamb neck fillet or boneless shoulder, cut into 4 cm pieces
• 4 lambs' kidneys, cored and quartered (optional, but traditional)
• 60 g beef tallow, plus 20 g melted for brushing
• 3 onions, thinly sliced
• 1 tbsp Worcestershire sauce
• 500 ml lamb or chicken stock
• 4 thyme sprigs and 2 bay leaves
• 1.2 kg floury potatoes (Russet or Yukon Gold), peeled
• Salt and black pepper

Method

1. Heat the oven to 160 °C (325 °F).
2. Season the lamb. Heat the 60 g of tallow in a large frying pan over high heat and brown the lamb in batches, then the kidneys briefly. Set aside.
3. Lower the heat and cook the onions in the same pan for 15 minutes, until soft and golden. Add the Worcestershire sauce and stock, and scrape up the browned bits.
4. Slice the potatoes 3 mm thick. A mandoline makes this quick. Don't rinse them; their starch is what thickens the sauce.
5. Layer the casserole: a third of the potatoes, then half the lamb, kidneys and onions with a thyme sprig and bay leaf, then another third of the potatoes, then the rest of the meat and onions. Pour in the stock.
6. Arrange the last of the potatoes on top in neat overlapping circles, like fish scales. Brush them with the melted tallow and season.
7. Cover with the lid and bake for 2 hours.
8. Take off the lid, raise the oven to 200 °C (400 °F), and bake for 30–40 minutes more, until the potatoes on top are crisp and deep golden. Rest for 10 minutes before serving.