Cut the cauliflower into “fries.” Trim the leaves and core. Slice the head into 1/2-inch planks, then cut into sticks about fry-size. Aim for similar thickness so everything cooks evenly.
Rinse and dry well. Briefly rinse the sticks and pat them very dry with paper towels.
Excess moisture fights against crisping.
Toss with oil. In a large bowl, add the cauliflower and drizzle with the oil. Toss until every piece looks lightly coated but not greasy.
Add the coating. Sprinkle in the cornstarch, garlic powder, onion powder, smoked paprika, salt, and pepper. Toss again until the spices and starch cling to the fries.
If using Parmesan, mix it in now.
Preheat the air fryer. Set to 390–400°F (200–205°C) for 3 minutes. A hot basket helps build a crust fast.
Arrange in a single layer. Add the cauliflower fries to the basket without crowding. Work in batches if needed.
Lightly mist with cooking spray for extra crispness, if desired.
Air fry until golden. Cook 10–14 minutes total, shaking the basket halfway through. Fries should be deeply golden at the edges and tender in the center. Thicker pieces may need a couple more minutes.
Season and serve. While hot, taste and add a pinch more salt if needed.
Finish with lemon, parsley, or a dusting of Parmesan. Serve with your favorite dip.