Slice the chicken thighs into bite-sized portions and place them in a large mixing bowl. In a separate bowl, whisk together gochujang paste, honey, brown sugar, tamari, garlic, and ginger until smooth to form the marinade. Pour half of this marinade over the chicken, stirring to coat thoroughly; if the mixture appears overly thick, stir in a splash of water to loosen it. Allow the chicken to marinate for 15 minutes. Warm the avocado oil in a skillet set over medium heat. Transfer the marinated chicken into the skillet and sauté for roughly 8 minutes until the meat is entirely cooked through. Pour in the remaining marinade along with the chopped green onions, stirring gently. Continue cooking for an additional 1–2 minutes, just until the onions have softened slightly and the sauce has thickened and begun to bubble. Remove from the heat and serve immediately over steamed white rice, finishing with a sprinkle of toasted sesame seeds if desired.