Peel potatoes, then cut into 1⁄3- inch slices and then into 1⁄3- inch sticks. Place the potatoes in a large bowl filled with water as you cut them to keep them from discoloring.
Soak the potatoes for at least 30 minutes and up to 24 hours in the refrigerator. This will remove the excess starch from the potatoes.
Fit a heavy stockpot with a deep- fry thermometer. Heat the oil over medium- high heat to 275° to 300°F. Have ready a rack set over a baking sheet.
Drain the potatoes and pat dry. Add 2 handfuls of potatoes to the hot oil. There should be at least 1 inch of oil above the potatoes. Cook until the potatoes are light brown, 5 to 7 minutes. Use a skimmer to remove the potatoes, gently shaking off excess oil, and put them on the rack to drain. Repeat with the rest of the potatoes. Let all the potatoes cool.
Increase the heat of the oil to 350°F.
Cook the potatoes again, 2 handfuls at a time, until golden brown, about 2 minutes. Remove, shake off the excess oil, place in a bowl, and season lightly with salt and pepper. Repeat with the rest of the potatoes and serve immediately.
Recipe from Guy Fieri Food by Guy Fieri/William Morrow, an imprint of HarperCollins, 2011.