Step 1: Marinate the Chicken

1. Pat the chicken thighs dry with paper towels. Season both sides with salt and pepper.
2. In a bowl, combine soy sauce, honey (or brown sugar), rice vinegar, minced garlic, grated ginger, sesame oil, and red pepper flakes (if using). Mix well.
3. Place the chicken in a resealable plastic bag or a shallow dish and pour the marinade over it. Seal the bag or cover the dish, and let it marinate in the refrigerator for at least 30 minutes (or up to 2 hours for more flavor).

Step 2: Cook the Chicken

1. In a large skillet, heat the vegetable oil over medium-high heat.
2. Remove the chicken from the marinade (reserve the marinade) and add it to the hot skillet. Sear for about 5–7 minutes on each side until golden brown and cooked through (internal temperature should reach 165°F / 74°C).
3. Once the chicken is cooked, pour the reserved marinade into the skillet. Bring it to a simmer and cook for an additional 2–3 minutes, allowing the sauce to thicken and caramelize slightly.

Step 3: Serve

1. Remove the chicken from the skillet and slice it if desired. Drizzle the thickened sauce over the chicken.
2. Garnish with sliced green onions and sesame seeds before serving.