Preheat the oven to 425 degrees. (If your oven is going to be set to a different temperature for the main dish, then use that temperature and just add or subtract a few minutes to the cooking time of your side dish.)

Slice the sweet potatoes the long way, making thin, long strips (no need to peel them). In a medium bowl, toss them with the oil, salt, and chili powder and/or cinnamon (optional). Bake them in a single layer on a baking sheet for 25 - 30 minutes, turning once, until they are lightly browned. For a crisper texture, broil them for 2 – 3 minutes before serving them. Serve them with ketchup or barbecue sauce, if desired.