Prep the turnips: Peel the turnips and cut them into fry-shaped sticks, about 1/2-inch thick.
Try to keep the pieces even so they cook at the same rate.
Soak briefly (optional but helpful): For extra-crispy fries, soak the cut turnips in cold water for 10–15 minutes. This pulls out some starch and helps with browning. Drain and pat very dry.
Season: In a large bowl, toss the turnip sticks with olive oil, garlic powder, paprika, onion powder, salt, and pepper until well coated.
Preheat the air fryer: Set to 400°F (200°C) for 3 minutes.
A hot basket helps crisp the fries from the start.
Arrange in the basket: Spread the fries in a single layer in the basket. Do not overcrowd. Cook in batches if needed.
Air-fry: Cook at 400°F for 12–16 minutes, shaking or flipping halfway. Start checking at 10 minutes. They’re done when the edges are golden and the centers are tender.
Finish: Taste and add a pinch more salt if needed.
Sprinkle with Parmesan or red pepper flakes if using. Serve hot with your favorite dip.