In a large bowl whisk together the soy sauce, sugar, garlic and peppercorns. Add the chicken to the bowl and turn to coat. Let marinate for at least 30 min and up to overnight.
Heat a 7-quart Dutch oven over medium heat, add the oil and heat through. Add the chicken thighs skin side down and drumsticks to the pot. Sear, until golden brown, about 5 minutes.
Flip the chicken then pour the marinade into the pot as well as the bay leaves and simmer for 15 minutes.
Add the vinegar then lower the heat to medium-low and cover the Dutch oven, cooking until the chicken is completely cooked through, about 20 to 25 minutes.
Remove the chicken from pot and set aside. Continue to cook the sauce until syrupy and reduced, about 10 minutes. Return the chicken to the sauce and top with green onions. Serve over rice.