Preheat your oven to 425°F (220°C). Grease a large baking sheet with cooking spray or line it with parchment paper.
Peel the sweet potatoes and cut them into ¼-inch wide sticks.
Soak the cut sweet potatoes in a large bowl of cold water for 30-60 minutes, then drain and dry thoroughly.
In a small bowl, mix together the cornstarch, garlic powder, smoked paprika, and pepper.
Toss the sweet potato sticks with olive oil until evenly coated, then sprinkle the cornstarch mixture over the fries and toss again.
Spread the fries in a single layer on the prepared baking sheet and bake for 15 minutes.
Flip each fry and return them to the oven for an additional 15 minutes, or until crispy and golden brown.
Remove from the oven and sprinkle with salt. Serve warm with your favorite dipping sauce.