Line a baking sheet with paper towels.

Cut each potato lengthwise into ¼-inch-thick slices, then cut these slices lengthwise into ¼-inch-thick sticks. Keep cuts uniform so the potatoes cook evenly.

Soak potatoes in cold water for 20 minutes. Drain and rinse potatoes in 3 changes of fresh cold water, draining after each rinse. (Don’t skip this step; it keeps fries from getting soggy.) Dry potatoes in a single layer on a towel-lined baking sheet, or pat/blot dry with towel.

First Fry:

Line a second baking sheet with paper towels.

Heat evoo in a heavy bottom 6-quart pot (like a Dutch oven) over medium heat until it reaches 250°F on a deep-fry thermometer.

Blot potatoes completely dry with more towels. Gently drop one-third of potatoes into the oil and increase the heat to medium high so that the oil goes back to 250°F. 

Cook, stirring occasionally with a skimmer or a large slotted spoon, for 2 to 3 minutes, until potatoes soften (you should be able to cut them with the side of the spoon), are slightly blistered, and creamier in color. Remove potatoes if they start to brown.

Scoop out potatoes, shake to drain off excess oil, transfer to prepared baking sheet, and arrange in a single layer. Fry remaining 2 batches of potatoes in the same manner, letting the oil return to 250°F before adding each batch.

Second Fry:

Heat oil until it reaches 360°F. (Once you drop in the fries, the temperature will lower to 350°F, which is the correct temperature for frying.) Line a baking sheet with paper towels.

Add one-third of potatoes and cook, stirring, for 1 to 2 minutes, until they turn golden-brown and become crisp.

Transfer fries to prepared baking sheet and sprinkle generously with salt. Fold the edges of the paper towels up and over the fries to make a little pouch, and shake well so salt is evenly distributed. 

Fry the remaining 2 batches of fries in the same manner, letting the oil return to 360°F before each batch. Serve immediately.