Preheat your air fryer to 380°F for about 3-5 minutes.
Pat the chicken thighs dry with paper towels to remove excess moisture.
In a small bowl, combine the ingredients for the teriyaki sauce: Soy sauce, Rice vinegar, Garlic (minced), Ginger (grated), Black pepper, and Sesame oil. Mix well.
Add about ⅓ of the prepared sauce to the chicken thighs and marinate for at least 30 minutes, if possible.
Pour the remaining sauce into a skillet and simmer over medium heat for 2 minutes. In a small bowl, mix 1 tablespoon of cornstarch with 2 teaspoons of water to make a slurry. Gradually whisk the slurry into the simmering sauce. The sauce will thicken within 2 minutes.
Remove the teriyaki sauce from the heat and set it aside.
Place the chicken thighs skin-side down in the air fryer basket, ensuring they are not overcrowded. Cook for 8-10 minutes.
Brush the chicken thighs generously with the prepared teriyaki sauce on both sides.
Cook for an additional 7-8 minutes to caramelize the sauce and create a sticky glaze.
Once done, garnish the chicken thighs with sesame seeds and chopped green onions.
Serve the chicken thighs over a bed of rice and enjoy!