Preparation

• Don’t peel the potatoes. Slice them into 1/4-inch-square strips that are as long as possible. Soak the sliced potatoes in ample water at room temperature for at least 8 hours and up to 24 hours.
  
• Remove the potatoes from the water and dry well with paper towels; otherwise, the oil will spatter.
• In a deep pot, heat the oil to 300°F (use a candy thermometer to check). Set a cooling rack over a baking sheet. Working in batches so as to not crowd the pot, fry the potatoes until cooked through but not colored, about 5 minutes. You’ll likely have to turn up the heat after adding the potatoes to keep the oil’s temperature near 300°F.
  
• Using a Chinese skimmer or a slotted spoon, carefully transfer the blanched potatoes to the cooling rack. Repeat until all the potatoes are blanched. Reserve the oil in the pot. The blanching can be done up to 2 hours ahead of the final frying; turn off the burner and keep the blanched potatoes at room temperature.
• To finish the fries, heat the oil to 375°F. Line a baking sheet with paper towels. Again working in batches, cook the potatoes until golden brown, 3 to 5 minutes. Immediately transfer the fries to the paper towels. Quickly season with salt (and pepper, if you like) and serve immediately