extremely crispy fries tossed in vinegar

Chop: Remove the potato skins. Use a serrated knife to cut the potatoes into 6 mm / 1/4 inch French fries. Notably 4,
While you cut the rest of the fries, keep the ones you cut in a dish of water so they don’t brown. Beyond this, there’s no real soaking required.
Put the potatoes in a colander and give them a quick rinsing under running water for around 15 to 20 seconds.
Put the fries in a big saucepan with 2 quarts or liters of cold tap water, vinegar, and salt; bring to a simmer. Raise the heat to high and boil, then quickly lower it to low so the surface ripples lightly (Note 5), but doesn’t produce large bubbles. After 10 minutes, transfer the fries to a colander using a slotted spoon; be cautious not to tip them into the colander, as this might cause them to shatter.
After five minutes, dry: Layer the fries onto two baking sheets that have been lined with tea towels. Wait 5 minutes and then steam dry.
Pot: In a pot that is at least 10cm/4″ tall, pour 3 cm / 1.2″ of oil. Make sure there is at least 7 cm / 3″ of space between the surface of the oil and the lip of the pot for safety reasons. Note 6: Divide the fries into three batches for cooking.
The first fry
The oil should be heated to 205°C (400°F) over medium-high heat.
*Note 7: 10-second pause* With a slotted spoon, drop one-third of the fries from Batch 1 into the oil. Do not add any more fries until after 10 seconds have passed; after that, add 1/3 of the fries from Batch 1.
Fry for 50 seconds, stirring once or twice, or until golden brown. Then, using a slotted spoon, transfer the mixture to two trays coated with paper towels and smooth it out evenly. Floppy white fries are still in store.
Bring the oil temperature back up to 205°C/400°F before frying the second and third batches in Fry 1.
The second fry step is to let the fries cool for half an hour.
Prepare a big basin for draining and mixing by lining it with paper towels.
Second Fry: Bring oil to a temperature of 205°C, or 400°F. Cook half of the French fries for 4 minutes, stirring twice, or until they are crispy and golden brown. After that, finish cooking the rest of the fries in the lined basin.
MAKE AND EAT!
Add salt, spice, or both to the fries. (Caution 8) Serve after tossing!
Crispiness of fries will not diminish as they cool. For an advice on cooking in bulk, see the note.