Add three inches (7.5 centimeters) of neutral oil to a Dutch oven and heat to 320°F (160°C). Line a sheet tray with a wire rack topped with paper towels.
neutral oil
In a small bowl, mix garlic powder, onion powder, dry mustard, smoked paprika, salt, and black pepper. Season both sides of the chicken with half of this blend. Reserve extra seasoning.
1 tablespoon garlic powder, 1 tablespoon onion powder, 1 teaspoon dry mustard, 1 teaspoon smoked paprika, 1 teaspoon kosher salt, 2 teaspoon black pepper
In one bowl, whisk together the egg and water. In another, combine rice flour, all-purpose flour, potato starch, baking powder, and reserved seasoning.
1 large egg, ¼ cup water, 1 cup rice flour, ½ cup all-purpose flour, ¼ cup potato starch, 2 teaspoon baking powder
Working one piece at a time: Dip the chicken into the egg wash, then coat it in the dry dredge. Press firmly to adhere. Shake off excess.
Fry one to two pieces at a time in 320°F (160°C) oil for 10-15 minutes, until the chicken reaches 155°F (68°C) internally. Transfer to the prepared rack and let cool for at least ten minutes or up to an hour.
Increase oil temperature to 360°F (182°C). Fry the chicken a second time until golden and crisp, about six minutes. Transfer to a fresh paper towel-lined rack.