Cut: Slice the sweet potato into ¼ inch thick pieces using a sharp chef's knife.
Rack: Place sliced sweet potato onto a wire cooling rack that's set on top of a baking sheet. This will allow air to circulate around the sweet potatoes.
Dry: Set on the middle rack of a 225°F (107°C) oven. Cook for 2 to 3 hours, flipping the potato pieces over after an hour, until potato is very dry and a bit crispy.
Notes
Store dried sweet potato loosely covered at room temp for up to 2 weeks (the longer they dry out in the oven, the longer you'll be able to store them).