Cut the chicken thighs into 1-inch thick pieces.
Transfer the chicken to a medium-sized mixing bowl. Add grated garlic, soy sauce, Shaoxing cooking wine, orange juice, salt, sugar, Chinese five-spice powder, and white pepper. Mix well and marinate for at least 1 hour or overnight.
For the Sichuan white peppercorn seasoning, heat a small pan over medium-low heat. Then, add Sichuan peppercorns and white peppercorns (if using whole). Toast for 2 to 3 minutes, making sure to constantly stir to prevent the spices from burning. Remove from the heat then grind into a powder using a spice grinder or mortar and pestle. Transfer to a bowl then add salt and sugar. Mix then set aside for later.
Preheat the air fryer to 400F (205C).
Crack an egg and separate the white from the yolk. Add the egg white to the marinated chicken and mix until combined.
To a small mixing bowl, add sweet potato starch. Coat each piece of chicken well on all sides. Optional, but highly recommended - sprinkle a few droplets of water into the sweet potato starch to create small beads. This will create crispy crunchy bits on the chicken.
Arrange the chicken in the air fryer basket, making sure they have ample space on all sides. Make sure they do not touch!
Spray both sides of the chicken with cooking oil spray then air fry for 5 minutes.
Flip the chicken then spray with cooking oil spray. Air fry for another 5 minutes.
Toss the Thai basil leaves into the air fryer with the chicken, and spray with cooking oil spray. Air fry for 5 more minutes or until brown and crispy.
Sprinkle the Sichuan white pepper seasoning on top of the chicken. Serve and enjoy!
