Preheat the oven to 375°F.
Cut the potato into very thin slices. Spray two baking sheets with cooking spray. Arrange the slices on the sheets in a single layer, and lightly coat the slices with cooking spray. Bake for 7 minutes, or until they've barely started to brown. Remove, turn them over, return to the oven, and bake 7 to 10 more minutes until lightly browned. Transfer to a bowl, and repeat with remaining potato slices.
Meanwhile, in a small bowl, combine the cumin, sugar, chili powder, and salt. Pour over the chips, toss well, and serve.