Waffle chips, called gaufrettes in France, are easiest to make using a mandoline equipped with a ruffled blade.
- 3 lb. Idaho potatoes, peeled
- Peanut oil
Using a ruffled blade in the lower plate of a mandoline, cut potato, creating a ridged surface. Twist potato 90 degrees, then slice against the grain through the potato. Discard the end slice, adjust the height of the lower plate (if necessary) to slice potatoes about 1⁄16" thick, then continue rotating and slicing potatoes until all have been sliced. Place waffle chips in a large nonreactive bowl and cover with water.
Heat about 4" oil in a heavy-bottomed pot over medium-high heat. Drain potatoes, then dry thoroughly with paper towels. Check oil temperature with a candy thermometer; when oil reaches 375°, fry potatoes in small batches until they are crisp and golden, about 3 minutes per batch. Drain chips on paper towels, sprinkle with salt, and serve warm or at room temperature.