Preheat the oven to 425°F. In a shallow baking pan, toss sweet potatoes with 2 Tbs. olive oil and 1/4 tsp. salt.

Arrange potatoes in a single layer, and roast until tender, about 25 minutes, stirring halfway through roasting time.

In a small bowl, whisk together the remaining 1 Tbs. olive oil and 1/2 tsp. salt, the chili powder, lime zest and lime juice.

Remove sweet potatoes from the oven. Drizzle the mixture over the sweet potatoes, and toss to coat evenly. Return the sweet potatoes to the oven, and bake an additional 5 minutes.