Triple-Cooked French Fries

1. 1Peel the potatoes and cut them into batons about 1.5 cm square. Keep them an even size or the thin ones burn while the thick ones are still raw inside.
2. 2Rinse under cold running water until the water runs clear, which washes off surface starch that would otherwise make them stick together.
3. 3Put them in a pan of cold salted water with the vinegar and bring to a gentle simmer. Cook for 8–12 minutes, until a knife slides in with almost no resistance and the edges are just starting to fray. The vinegar keeps them from collapsing entirely.
4. 4Drain very carefully and spread on a rack in a single layer. Cool completely, then refrigerate uncovered for at least 30 minutes — an hour is better. You're drying the surface out, and this is the step that creates the crust.
5. 5Heat the oil to 130°C. Fry in batches for 5–6 minutes until pale and dry-looking but not coloured. Lift out and cool on the rack again for at least 20 minutes. They can be frozen at this point.
6. 6Raise the oil to 180°C. Fry in batches again for 3–4 minutes, until deep golden and audibly crisp when you knock two together.
7. 7Drain on a rack, never on kitchen paper, and salt heavily the second they come out of the oil — that's when the salt actually sticks.

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