Peel potatoes on the sides, leaving the ends with the skin on. Cut the potatoes into 1/3-inch slices and then slice into 1/3-inch sticks.
Fill a large bowl with water and soak potatoes, submerged, for at least 30 minutes up to 24 hours. This will help remove the excess starch from the potatoes and keep them from oxidizing.
Heat a heavy stock pot fitted with a deep-fry thermometer with oil to 325 degrees F.
Remove potatoes from the water, and pat dry to remove excess water. Add 2 handfuls of potatoes to hot oil. There should be at least 1-inch of oil above the potatoes. Par cook until potatoes are light brown, 5 to 7 minutes. Remove potatoes, gently shaking off excess oil and let drain on rack. Repeat until all of the potatoes are par cooked.
Raise heat of oil to 350 degrees F.
Cook potatoes again, 2 handfuls at a time, until golden brown, about 2 minutes. Remove from oil, shake off excess oil, and season lightly in a bowl with salt and pepper. Repeat until all potatoes are cooked.