Preheat your oven to 425°F (220°C). Line two large baking sheets with parchment paper or lightly spray with cooking spray to prevent sticking. Using two sheets helps avoid overcrowding the fries.

Wash and peel the sweet potatoes if you prefer them without skin. Cut each sweet potato into even 1/4 to 1/2-inch thick sticks. Aim for uniform size so they cook at the same rate.

Place the cut fries into a large bowl and cover with cold water. Let them sit for 10 minutes — this step helps remove excess surface starch and improves crisping.

Drain the fries and pat them thoroughly dry with clean kitchen towels or paper towels. Moisture is the enemy of crispiness, so be thorough here.

Toss the dried fries with cornstarch in a large bowl until they're lightly and evenly coated. Shake off any excess cornstarch.

In a small bowl, whisk together the olive oil, salt, black pepper, paprika, garlic powder, and cayenne if using. Pour this mixture over the fries and toss to coat every piece evenly.

Spread the fries out in a single layer on the prepared baking sheets, ensuring they aren't touching too much. Crowding traps steam and prevents crisping.

Bake on the middle rack for 20 minutes, then rotate the pans and flip the fries with a spatula. Continue baking for another 10-15 minutes until the fries are golden and edges are crisp. Exact time depends on thickness and oven variations.

For extra crispiness, switch the oven to broil for 1-2 minutes at the end, watching closely to avoid burning — this step is optional but gives a nice finish.

Remove the fries from the oven and let them rest on the baking sheets for 3 minutes to firm up. Sprinkle with chopped parsley or chives and an extra pinch of salt if desired.

Serve immediately with your favorite dip — ketchup, garlic aioli, or a yogurt-based dip all pair wonderfully.