1. Heat wok with ¼ cup cooking oil over high heat and place marinated chicken pieces in. Cook all sides for approximately 5 minutes, and then pour in the retained soy and garlic marinade from the chicken, along with 1½ cup water and bring to boil.
2. When the liquid in the pan starts to boil, add the dried bay leaves and whole peppercorn, turning the heat down and leave to simmer for 30 minutes or until the chicken is tender.
3. After 30 minutes of simmering, add in the vinegar. Stir thoroughly and allow to simmer for a further 10 minutes.
4. Lastly, add in sugar and salt to taste. Stir through and turn heat off.