Set your oven to 425°F (220°C) and slip a baking sheet inside to warm up.
Cut the sweet potatoes into evenly sized 1/4 inch thick strips, peeling them first if you choose.
Soak the fries in cold water for 30 minutes to draw out starch for better crisping.
Drain the fries and dry them thoroughly with paper towels, then toss in a large bowl with olive oil, garlic powder, paprika, salt, pepper, and cornstarch if using.
Take out the hot baking sheet and spread the fries out in a single layer without crowding.
Bake for 25 to 30 minutes, turning the fries halfway through until they turn crisp and golden.
Remove fries from the oven and allow them to rest for a few minutes before serving to enjoy maximum crispiness.