Cut the potatoes: peel and cut the potatoes into chips with about a 2 cm square cross-section.
Simmer the chips: place the cut potatoes into a pot of cold water. Put the pot on medium heat and bring it to a simmer. Cook until the chips are almost falling apart, which should take approximately 20 to 30 minutes, depending on the type of potato.
Remove Starch: while simmering, use a ladle to skim off any potato starch that floats to the top and discard it.
Dry the chips: carefully remove the chips with a spider or slotted spoon and place them on a cooling rack to dry out. Then, place them in the freezer for at least one hour to remove more moisture.
First fry: Heat a deep-fat fryer or a deep pan with oil to a depth of around 10 centimetres. Bring the oil to a temperature of 140ºC. Fry the chips in small batches until a light crust forms, which should take approximately five minutes. Remove the chips from the oil and drain them on kitchen paper.
Freeze again: Place the chips on a cooling rack and put them back in the freezer for at least one hour. (At this stage, the chips can be kept in the fridge for up to three days if you don’t plan to cook and serve them immediately.)
Second fry: Heat the oil in the deep-fat fryer or deep pan to 190ºC. Fry the chips until they are golden brown, which should take about seven minutes.
Season and serve: Drain the chips, sprinkle them with sea salt, and serve immediately.
