1.5kg/3lb 5oz potatoes, cut into large chunks
4 tbsp duck fat or olive oil
1 Put the potatoes in a large pan of salted water. Cover and bring to the boil. Boil for 6–7 minutes, then drain well.
2 Return the potatoes to the warm pan and shake them roughly, so they become fluffy around the edges.
3 Preheat the oven to 220°C/425°F/Gas 7.
4 Heat the fat or oil in a large roasting pan on the hob. When it sizzles, add the potatoes. Baste the potatoes, taking care as the fat will splutter.
5 Roast the potatoes in the oven for 1 hour, then reduce the oven temperature to 200°C/400°F/Gas 6 and roast for 40 minutes. Turn the potatoes only once during cooking to crisp and brown them.
6 Season with a little salt just before serving.