Preheat your oven to 400°F (200°C).
In a large bowl, whisk together the sweet chili sauce, soy sauce, honey, rice vinegar, minced garlic, ground ginger, and black pepper until well combined.
Add the chicken thighs to the bowl and toss to coat them evenly in the marinade. Let them marinate for at least 30 minutes, or up to 2 hours in the refrigerator for more flavor.
Heat the vegetable oil in a large oven-safe skillet over medium-high heat. Once hot, add the marinated chicken thighs skin-side down and sear for about 5 minutes until the skin is golden brown.
Flip the chicken thighs over and pour any remaining marinade over them. Transfer the skillet to the preheated oven and bake for 25-30 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (75°C).
If desired, broil the chicken for an additional 2-3 minutes to crisp up the skin.
Remove from the oven and let the chicken rest for 5 minutes before serving. Garnish with sesame seeds and sliced green onions if desired.