Sweet Potato Chips

Preheat oven to 350°. Place two wire racks on two large rimmed baking sheets. Toss sweet potatoes in oil until evenly coated. In a separate large bowl, whisk together spices and cornstarch. Add sweet potatoes and toss until evenly coated in spice mixture. Place sweet potatoes on wire racks in a single layer. Bake for 25 to 35 minutes, until sweet potatoes look crispy and dry to touch. (They'll continue to crisp as they cool.) While the sweet potatoes cool, make dip: Fold green onions into sour cream and serve with sweet potato chips.