Allow to sit for 5 minutes.
- Meanwhile, add the oil to a rimmed baking sheet and
place it in the oven to preheat. Combine the garlic
powder, paprika, black pepper, cayenne, flour,
cornstarch, baking powder, and 1 tablespoon salt in a
large bowl and whisk to combine.
- Drain the potatoes and return them to the bowl. Sprinkle
half the flour mixture over them and turn a few times.
Sprinkle the remaining flour mixture over them and fold
gently until all the potatoes are coated. Let them sit in the
flour mixture for at least 5 minutes, tossing occasionally,
until a thick layer of coating has built up around each
plank.
- Working in batches, transfer the potatoes to a fine-mesh
strainer and shake gently over the sink to remove the
excess flour, then transfer to a large bowl.
- Carefully remove the baking sheet from the oven (the oil
should be lightly smoking) and add the potato planks in a
single layer. Return the baking sheet to the oven and
bake until the bottom side of the potatoes is light golden
brown, about 10 minutes. Remove from the oven and flip
the potatoes using a thin flexible spatula. Return to the
oven and continue to bake until both sides are deep
golden brown and crisp, 10 to 15 minutes longer. Drain
on paper towels, season with salt to taste, and serve
immediately.
