A roast potato is one of the most ruthless tests a cook can set themselves. The technique is short; the discipline is everything.

Peel a kilogram of floury potatoes — Maris Piper or King Edward — and cut them into rough generous chunks. Parboil in well-salted water for ten minutes until the edges are just starting to fluff. Drain. Shake the colander hard until the surfaces look rough and shaggy — this is where the crisp comes from.

Heat a tray of duck fat or a neutral oil in a hot oven at 220°C until it is shimmering. Tip the potatoes in carefully, turn each one in the fat, and roast for forty-five minutes, turning twice, until they are deep bronzed and glassy.

Salt at the end, never the beginning. A scatter of chopped rosemary in the last five minutes is the only seasoning a properly roasted potato actually needs.