(Any sweet potato seems to work just as well.)
Peel (if you like) a purple sweet potato and slice it 1/8" thick.
Toss in 1 tablespoon of olive oil (per potato) and sprinkle with salt and pepper (or whatever else you fancy) to taste.
Spread in a layer (without overlapping) on a parchment-lined cookie sheet and bake 70 minutes at 250F.
I baked them an extra 10 minutes to be sure they'd be crisp, but don't know if it was necessary because they became crisper once they cooled.
