Preheat the oven: Set to 300°F (150°C) with racks in the upper and lower thirds. Line two large baking sheets with parchment for even browning and easy cleanup.

Slice the sweet potatoes: Use a mandoline set to 1/16–1/8 inch (1.5–3 mm). If using a knife, take your time and keep slices as uniform as possible. Even thickness = even crisping.

Dry the slices: Pat slices dry with paper towels. Removing surface moisture helps them crisp instead of steam.

Season: Toss slices in a large bowl with oil, salt, pepper, and any optional spices. Coat lightly and evenly—no puddles of oil.

Arrange on sheets: Lay slices in a single layer with no overlap. Crowding leads to soft chips.

Bake low and slow: Bake 18–22 minutes, then rotate pans and flip the slices. Continue 15–25 minutes more, watching closely. They’re done when edges are deep golden and centers look mostly dry.

Finish and crisp: Turn off the oven, crack the door, and let the chips sit inside 5–10 minutes. This gentle dry-out step boosts crunch.

Cool completely: Transfer to a rack and let them cool. They crisp further as they cool. Taste and add a pinch of salt if needed.