Cut: Peel the potatoes. Cut into 6 mm / 1/4" French fries using a serrated knife. (Note 4)

Keep cut fries submerged in a bowl of water to prevent them from going brown while you cut the remainder. (No need for actual soaking beyond this.)

Rinse: Transfer potatoes to a colander and rinse under tap water for 15 - 20 seconds.

Simmer: Place fries in a large pot with 2 litres/quarts of cold tap water, vinegar and salt. Bring to a boil over high heat then immediately reduce stove to low so the surface is rippling gently (Note 5), not big bubbles. Cook for 10 minutes then carefully remove using a slotted spoon into a colander (do not tip into colander, fries will break).

Dry 5 min: Spread the fries on 2 tea towel lined trays. Leave to steam dry for 5 minutes.

Pot: Pour 3 cm / 1.2" of oil in a pot that is at least 10cm/4" high (⚠️for safety, need at least 7 cm / 3" from oil surface to rim of pot, Note 6)

Separate the fries into 3 Batches (for cooking).

Heat oil to 205°C/400°F over medium high heat.

⚠️10 sec pause (Note 7): Lower 1/3 of Batch 1 fries into the oil using a slotted spoon. WAIT 10 seconds, add another 1/3 of the fries, wait 10 seconds, then add the remaining Batch 1 fries.

50 sec fry: Fry for 50 seconds, moving them around once or twice. Then remove with a slotted spoon onto 2 paper towel lined trays, spread out in a single layer. The fries will still be white and floppy.

Repeat Fry #1 with Batches 2 and 3, ensuring the oil is back at 205°C/400°F before cooking.

30 min cool: Leaves fries to cool for 30 minutes.

Line a large bowl with paper towels - for draining and tossing.

Fry #2: Heat oil to 205°C/400°F. Fry half the French fries for 4 minutes, moving them around twice, or until golden brown and crispy. Drain in the lined bowl, then repeat with remaining fries.

Sprinkle fries with salt or seasoning or choice. (Note 8) Toss and serve!

Fries will stay crispy even once cool. See note for large batch cooking tip.