Prepare the Marinade: In a bowl, mix the gochujang, soy sauce, honey, sesame oil, rice vinegar, garlic, and ginger.
Add the chicken thighs to the bowl, making sure they are evenly coated with the marinade. Let them marinate for at least 30 minutes, preferably longer (up to overnight in the refrigerator).
Preheat the Air Fryer: Preheat your air fryer to 190°C (375°F) for about 5 minutes.
Place the chicken thighs in the air fryer basket, skin side down. Cook for 12-15 minutes, then flip the chicken thighs and cook for an additional 10-12 minutes, or until the internal temperature reaches 75°C (165°F) and the skin is crispy.
Remove the chicken thighs from the air fryer and let them rest for a few minutes. Garnish with sesame seeds and chopped green onion if desired.