Pour oil to a depth of 2" into a 6-qt. heavy-bottomed dutch oven and heat over medium-high heat until the temperature registers 375° on a deep-fry thermometer. Add all the potatoes and cook, turning occasionally and maintaining an oil temperature of 325° (adding the potatoes will cause the temperature to drop), until pale and tender, about 8 minutes. Using a slotted spoon, transfer fries to a rack set over a rimmed baking sheet and refrigerate until chilled, about 1 hour.
Increase oil temperature to 385°. Working in small batches, add potatoes again; cook, stirring until golden brown and crisp, about 2 minutes. Using a slotted spoon, transfer fries to a rack set over a rimmed baking sheet. Season fries with salt.