Peel sweet potatoes if desired and cut into even fry-sized sticks for uniform cooking.
Place cut fries in a bowl of cold water and soak for at least 30 minutes. Drain and pat completely dry with paper towels.
Toss fries with olive oil, salt, paprika, garlic powder, black pepper, and cornstarch (if using). Coat evenly.
Preheat air fryer to 380°F (193°C) for 3–5 minutes.
Place fries in a single layer in the basket. Cook for 12–15 minutes, shaking halfway through, until golden and crispy. Avoid overcrowding.
Remove from air fryer, adjust seasoning if needed, and serve hot with your favorite dip.