Preheat your oven to 220°C (425°F/gas 7).
Peel (if you like) and cut the Potatoes into even-sized chunks so they cook uniformly.
Place the cut Potatoes in a large saucepan, cover with cold water and add a generous pinch of Salt. Bring to the boil, then simmer for 8–10 minutes until the edges are just tender but the centers still firm.
Drain the Potatoes well in a colander, then give them a good shake or rough up the surfaces with a fork to create fluffy, uneven edges that will crisp up in the oven.
While the potatoes drain, put a roasting tray with a good helping of Goose Fat into the hot oven and heat until it is very hot and shimmering.
Carefully transfer the prepared Potatoes into the hot Goose Fat (watch for splatter) and turn them to coat thoroughly. Spread them out in a single layer so they have room to crisp.
Roast for 40–50 minutes, turning every 15 minutes or so, until the potatoes are deeply golden and crisp all over.
Remove from the oven and immediately season with flaky Sea Salt. Toss gently and serve straight away for best texture.
