Combine balsamic vinegar, soy sauce, honey, garlic, Sriracha, and ginger in a small bowl and mix well.

Place chicken thighs in a large bowl and pour half of the marinade over the chicken, ensuring it is well coated. Marinate for at least 2 hours or overnight for best results.

Reserve the remaining marinade for later use as a sauce.

Preheat the air fryer to 400°F.

Remove chicken from marinade and transfer to the air fryer basket.

Cook in batches for 14 minutes, turning halfway through, until cooked through in the center.

Meanwhile, place the remaining marinade in a small pot and cook over medium-low heat until it reduces and thickens, about 1-2 minutes.

Drizzle the cooked chicken with the reduced sauce and garnish with sliced scallions before serving.