In a large bowl, combine soy sauce, hoisin sauce, oyster sauce, honey, brown sugar, five-spice powder, garlic, ginger, and sesame oil. Mix well to create the marinade.
Add the chicken thighs to the marinade, ensuring they are well coated. Cover with plastic wrap and let it marinate in the refrigerator for at least 1 hour (or overnight for best flavor).
Preheat your grill or oven to 400°F (200°C).
Remove the chicken from the marinade and reserve the marinade for basting.
Grill the chicken for about 6-7 minutes on each side, or until fully cooked, basting with the reserved marinade every few minutes for extra flavor and stickiness.
If using an oven, place the chicken on a baking tray lined with parchment paper and roast for about 25-30 minutes, flipping once halfway through and basting with the marinade.
Once golden and sticky, remove the chicken from heat and let it rest for 5 minutes.
Slice the chicken into strips and serve on a platter, garnished with green onions and sesame seeds.
Notes
For a vegetarian option, substitute oyster sauce with mushroom sauce.