Preheat the air fryer to 380°F / 193°C for 3 minutes.
Place the shredded potatoes in a clean kitchen towel and squeeze firmly over the sink until no more water drips out.
Transfer the dried potatoes to a bowl and toss with cornstarch, oil, salt, black pepper, and onion powder until evenly coated.
Divide the mixture into 3 portions and press each firmly into a flat oval patty about 1/2 inch thick.
Place the patties in a single layer in the air fryer basket and air fry for 12 to 15 minutes, flipping halfway, until golden brown and crisp on both sides.
Check at 12 minutes — the edges should be deeply golden and crisp, and add 2 to 3 more minutes if needed.
Serve immediately while hot and crispy.