Ideally, Belgian fries have a golden to golden-brown appearance, and a bite through the crispy outside should reveal a soft inside. The ratio of crispy exterior to soft interior is determined by the thickness of the fries, which can range from 10–13 mm and as thin as 5 mm.
Potatoes (those with a high dry matter content such as Russet or Maris Piper work best)
Cooking oil
Salt
Prefry potatoes for about 7–12 minutes in 130–186 °C (275°F–365°F) fat to cook the inner part without burning the outside. When the fries are added to the oil, the oil at first cools quickly and is kept at low temperature to prevent the potatoes from burning. The fries should stay a pale beige to yellow color and not be too dry.
7–12 minutes
Remove fries from oil, toss to avoid clumping, and allow to cool down and dry for at least 30 minutes to make the fries more crispy and less greasy later. This intermediate product can be either frozen for 'instant' deep-frying later, or as several batches of 'pre-fried' fries prepared for rapid frying and almost serving later.
30 minutes
Deep-fry for about 2–5 minutes in 175–195 °C fat, depending on the initial temperature of the fries. Work in small enough batches to keep the oil at 125–160 °C for the first 30 seconds of frying. You want to have enough cooking time (7–16 minutes) without allowing the fries to become too greasy.
2–5 minutes
Cool and dry the fries for at least 25 minutes to make them more crispy later. Cooling the fries may help precipitate the oil making it less greasy later.
25 minutes
Sturdily toss, centrifuge by spinning around in a container, and toss a second time to remove excessive fat.