Scrub the sweet potatoes and leave them whole and unpeeled. Set them in a steamer basket over boiling water, cover, and steam 40 to 50 minutes, until a skewer slides through the thickest part with no resistance.

Cool on the counter until you can handle them, then refrigerate overnight. Cold, set sweet potato slices cleanly, while warm sweet potato tears apart. Do not skip this step.

Slip the skins off with your fingers. They come away easily once the sweet potatoes are cold.

Slice each sweet potato lengthwise into planks a firm ⅓ inch thick. Thinner slices dry into brittle chips and thicker ones will not dry through the middle.

Lay the slices in a single layer on drying racks with space between them so air moves on all sides.

SUN DRYING: set the racks in direct sun with moving air for 3 to 5 dry days, flipping once a day, covering with mesh, and bringing them indoors each evening.

DEHYDRATOR: dry at 135F for 8 to 12 hours, flipping the slices and rotating the trays halfway through. Start checking at 8 hours.

OVEN: set the oven to its lowest temperature, ideally 170F or below, and prop the door open a couple of inches. Dry on a wire rack set over a sheet pan for 4 to 6 hours, flipping every 90 minutes.

They are done when a cooled slice bends most of the way over and springs back without cracking, feels dry and slightly tacky, and shows a uniformly dense dark amber interior when torn in half.

Pile the finished slices loosely in a jar, seal it, and leave it on the counter for 3 to 4 days, shaking once a day. This evens out the moisture across the batch.

If condensation appears inside the jar, the slices were not dry enough. Return them to the racks for a few more hours.