In a bowl, whisk soy sauce, brown sugar, water, garlic, ginger, rice vinegar, sesame oil, pepper, and bay leaves.
Add chicken thighs and marinate at least 30 minutes (or overnight for best flavor).
Heat oil in a pan and sear chicken 2–3 minutes per side (optional but recommended).
Place chicken in a deep pan or baking dish.
Pour marinade over chicken.
Cook on stovetop (simmer 25–35 minutes) or bake at 375°F (190°C) for 35–45 minutes until fully cooked.
Remove chicken and simmer sauce until slightly thickened.
Return chicken to coat in glaze.
Serve hot over rice with green onions and sesame seeds.