01 - Rinse the cut potatoes under cold water to remove excess starch. Drain thoroughly and pat dry with a clean kitchen towel.
02 - Warm vegetable oil in a deep fryer or large, heavy-bottomed pot to 350°F (175°C).
03 - Fry the potato strips in batches for 4–5 minutes until pale golden and tender. Remove with a slotted spoon and drain on paper towels.
04 - Raise oil temperature to 375°F (190°C) for final frying.
05 - Fry the potatoes again in batches for 2–3 minutes until deep golden and crisp.
06 - Drain fries thoroughly, toss immediately with sea salt, and serve hot with ketchup on the side.