Preheat the air fryer to 380°F for 3 minutes if the appliance manual recommends preheating.
Cut peeled sweet potatoes into batons about 1/4 inch thick and 3 inches long, removing very thin tapered scraps so the batch cooks evenly.
Blot the batons dry. Toss first with cornstarch until dusty, then with oil, paprika, garlic powder, half the salt and pepper.
Arrange a single uncrowded layer with visible gaps. Divide the potatoes into two or three batches rather than piling them.
Cook 12 to 18 minutes, shaking and turning at 5 and 10 minutes. Begin checking thin pieces at 12 minutes and remove them as they brown.
Transfer to a rack or open platter, add the remaining salt, and rest 3 minutes so steam escapes before serving.
