In a bowl, whisk the vinegar, honey, soy sauce, sesame oil, chili garlic sauce and garlic until smooth. Pour half the marinade into a large plastic zipper bag; set aside the other half of the sauce.
Place the chicken thighs into the bag containing half the marinade, squeeze all the air out of the bag, and seal. Shake a few times to coat chicken; refrigerate for 1 hour, turning bag once or twice.
Preheat oven to 425 degrees F.
In a small saucepan, pour the reserved marinade over medium heat. Bring to a boil and cook for 3-5 minutes, stirring often, until sauce is thickened.
Place chicken in a 9x13-inch baking dish; discard used marinade. Brush chicken with 1/3 of the thickened marinade from the saucepan.
Bake 30 minutes, basting one more time after 10 minutes.
Let stand for 5-10 minutes.
Sprinkle with green onions.