Wash the potatoes and dry them thoroughly. First cut lengthways into 1 cm thick slices, then cut each slice into 1 cm wide sticks.
Heat the oil in a deep, heavy pan. Dip the potato sticks in small portions in the moderately hot oil and deep-fry for 4 minutes until light yellow. Carefully lift the french fries out of the oil with tongs and let them drain on kitchen paper.
Just before serving, heat the oil again. Fry the french fries in portions until they are crispy and golden yellow. Drain on kitchen paper. Apply immediately. The frying time is 6 - 8 minutes.