Pat the chicken thighs dry with a paper towel to remove any surface moisture.
In a bowl, whisk together potato starch, garlic powder, and onion powder; then toss the thighs until thoroughly coated.
Arrange the coated thighs in a single layer within the air fryer basket, leaving space between each piece.
Set the air fryer to 400 °F and cook for 25 minutes, flipping the thighs halfway through to ensure even crisping.
About 3 minutes before the thighs are finished, combine soy sauce, brown sugar, garlic powder, rice wine vinegar, black pepper, and water in a small saucepan over medium heat. Stir continuously until the mixture bubbles and melds; it should be fluid and glossy, not heavily thickened.
Once the thighs are cooked through and crispy, remove them from the air fryer and immediately toss them in the warm sauce until each piece is thoroughly glazed.
Serve the thighs hot for optimal texture and flavor.