Marinate chicken in soy sauce, garlic, and pepper for at least 30 minutes.
Heat oil in a large pot over medium heat.
Add sliced onions and sauté until translucent.
Add marinated chicken and brown on all sides.
Pour in vinegar and simmer without stirring for 3-4 minutes.
Add water, bay leaves, and peppercorns; bring to a boil.
Reduce heat, cover, and simmer for 30 minutes until chicken is tender.
Season with salt to taste and serve hot over rice.