1Place sweet potatoes in large bowl. Add enough cold water to cover. Refrigerate 30 minutes. Drain well. Pat dry with paper towels.
2Preheat oven to 425°F. Line 2 shallow baking pans with parchment paper. Set aside. Place sweet potato fries in large bowl. Drizzle with oil and sprinkle with black pepper; toss to coat. Sprinkle with cornstarch, toss until fries are well coated. Arrange fries in single layer on prepared pans.
3Bake 15 minutes. Flip fries using thin spatula. Rotate pans. Bake 16 to 20 minutes longer or until lightly browned. Transfer hot fries to large bowl. Add cinnamon and salt, tossing to coat fries evenly. Serve immediately.