In a bowl, combine chicken, soy sauce and vinegar. Marinate for at least 30 minutes.
Heat oil in a pan. Saute onion and garlic.
Once onion softens, add marinated chicken. Saute until light brown.
Pour remaining marinade, and then add whole peppercorn, dried bay leaves, and buko juice. Let boil.
Adjust heat to between low to medium and continue to cook for 15 minutes.
Add green onions. Cook for 5 minutes.
Transfer to a serving plate. Share and enjoy!