Heat the sauce in a small pot until just starting to boil. Whisk in the arrowroot powder until smooth. Remove from heat.
Portion the teriyaki sauce over the chicken thighs.
Cook for 40 minutes or until chicken thighs reach 170 degrees Fahrenheit on a meat thermometer.
Broil for 2-3 minutes watching closely.
Remove from the oven and serve.
Video
Notes
If you want more sauce to pour on top, whisk together another half batch of the gluten-free teriyaki sauce and combine 1tsp of arrowroot powder. Heat at a rolling boil until sticky.