Plunge the cut potatoes into a pan of boiling water to parboil, about 3 minutes. Drain well.
Toss the drained chips in the cornflour and coat thoroughly. Add a few drops of water to moisten, if needed.
Heat the oil in a pan to 160 degrees C. Once hot, add the chips and fry for about 7 minutes, till browned. (Alternatively, spray the chips with a bit of oil, place on a greased baking tray, then bake in a hot oven till crispy, turning once.)