Place the cut chips in a bowl of cold water and, when you have finished cutting them all, leave the bowl under the cold tap for five minutes to remove excess starch. Bring a large pan of unsalted water to a simmer and drop in the chips. Cook until the potatoes are soft, ideally to that point just before they start falling apart. With a slotted spoon, carefully lift out the chips and place on a tray, board or, best of all, a cake rack, then leave to cool. Once cool, place in the fridge for at least half an hour.
Preheat the fryer to 130C. Cook the cold chips at this level until they take on a dry appearance on their surface - you don't want them to colour at all. Drain, and leave to cool again. When cool, refrigerate again for at least half an hour.
Increase the temperature of the oil in the fryer to 190C. Plunge the cold chips in this and cook until golden brown and crisp. Drain, salt and serve at once."