1. Line with foil a baking tray that fits inside your toaster oven (or use a small disposable foil tin). Place tray in toaster oven and preheat to 450°F, preferably on the roast or bake setting. Put potato wedges in a medium bowl, drizzle with oil and sprinkle with sugar, chili powder, 1/2 tsp. salt and pepper to taste. Toss to coat.
2. Carefully remove tray from oven and arrange sweet potato wedges in a single layer. Sprinkle with any seasoning remaining in bowl. Roast potato wedges, flipping once, until tender and browned (they may be slightly charred in spots), 20 to 25 minutes. Transfer to a serving plate and let cool slightly before serving.