Preheat the oven to 375 F.
Combine the coconut aminos, vinegar, coconut sugar, garlic and ginger powder and set aside.
Prepare the chicken thighs by patting dry and seasoning with salt and pepper. Add the arrowroot starch and toss to coat the chicken on all sides.
Using a large, oven-safe skillet, heat the avocado oil over medium-high heat. Once the oil is shimmering, add the chicken, and skin side down. Cook for about 4-6 minutes to thoroughly crisp the skin. Carefully flip the thighs and cook for another 3-4 minutes on the other side.
Add the teriyaki sauce to the skillet and simmer for a few minutes to allow the sauce to start to thicken. Toss the chicken to coat.
Transfer the skillet to the oven for 15-20 minutes. The chicken thighs should be cooked through to 165 F, and the meat should be tender.
Carefully remove from the oven and allow to rest for a few minutes before serving topped with green onion with a side of your choice.