In a small bowl combine the balsamic vinegar, soy sauce, honey, garlic, Sriracha, and ginger and mix well.
Pour half of the marinade (1/4 cup) into a large bowl with the chicken thighs, covering all the meat and marinate at least 2 hours, or as long as overnight. Reserve the remaining sauce for later.
Preheat the air fryer to 400F.
Remove the chicken from the marinade and transfer to the air fryer basket.
Cook in batches for 14 minutes, turning halfway until cooked through in the center.
Meanwhile, place the remaining sauce in a small pot and cook over medium-low heat until it reduces slightly and thickens, about 1 to 2 minutes.
To serve, drizzle the sauce over the chicken and top with scallions.