1Heat the oven to 450°F and arrange the racks in the upper and lower third. Coat 2 baking sheets with 1 teaspoon of the oil each; set aside.
2Place sweet potatoes in a large bowl, drizzle with vinegar and remaining vegetable oil, sprinkle with salt and pepper, and toss to coat. Evenly divide potatoes between the prepared baking sheets, spreading in a single layer. Bake, rotating the pans halfway through, until the chips are browned and the edges are crisp, about 25 minutes.