Cut potatoes plank style - 1/4" thick by 1/2" wide. Place in a large bowl of cold ice water and chill in fridge for 30 minutes, changing water 3 times. Drain, pat completely dry.

Place cornstarch in a large bowl and gently toss with potatoes to coat. Shake off excess and place on a wire rack (over a baking sheet) and let sit for 20 minutes to allow the cornstarch to form a white coating over the potatoes.

Choose a heavy bottom sauce pan and fill at least 4" deep with oil (making sure you have 3-4" headroom at top to allow for the oil to bubble up). Bring oil up to 330°F using a deep-fry thermometer, then carefully drop a third of the potatoes into the oil. The ideal temperature of the oil is 325°F for cooking, however by increasing the heat initially at the start it will compensate for the drop in temperature once you add the potatoes.

Gently stir the potatoes around and remove after 3-5 minutes when they can easily be cut with the side of fork, and their surface just starts to blister (but not brown). Use a mesh strainer and remove the potatoes from the oil, and place on a paper towel lined pan wire rack (with a baking sheet underneath). Fry the remaining potatoes the same way. Be sure not cook too many at once - this will dramatically lower the temperature of the oil, you want to maintain the temperature at 325°F during this initial fry. Let the slices sit for at least 10 minutes before the second fry (this will firm up the cornstarch coating).

Increase oil temperature to 375°F then fry in batches for 1-2 minutes or until potatoes turn golden brown and are crisp. The ideal temperature of the oil for the second frying stage is 350°F, however by increasing the heat initially at the start it will compensate for the drop in temperature once you add the potatoes.

Immediately strain out and place on wire rack (remove paper towel), shaking to remove any excess oil. Place fries into a bowl and generously sprinkle with salt. Repeat with remaining potatoes.