Peel and wash the potatoes and cut them first into approx. 1 cm thick slices, then lengthwise into sticks. In cold water l
Bring vinegar and 2 l water to the boil in a large pot. Drain the potatoes and cook in the vinegar water for about 10 minutes. Lift them out with a skimmer, let them drain and put them on a clean tea towel.
Heat the oil in a deep fryer or a wide pot to about 180°C (it is at the right temperature when small bubbles rise from a wooden stick held inside). Fry the potatoes in it in portions for about 1 minute. Lift them out and let them drip off. Spread the potatoes on several sheets of baking paper with a little distance between them. Layer the sheets on a tray and freeze for about 1 hour.
For the second deep-frying cycle, heat the oil again to approx. 180 °C. Carefully slide the frozen French fries into the fat in portions and deep-fry for approx. 7 minutes until golden brown. Lift out the fries, drain and place in a bowl. Season with salt and pepper.
The frost destroys the cell structures, and the water can evaporate better during the second deep-frying cycle. The result: extra crispy fries.