Creating Filipino Chicken Adobo is simple when you follow these steps:

1. Marinate the Chicken: In a large bowl, combine chicken, soy sauce, vinegar, minced garlic, and black peppercorns. Mix well and let marinate for at least 30 minutes, preferably in the refrigerator.
2. Heat the Oil: In a large pot or Dutch oven, heat the vegetable oil over medium heat.
3. Sauté the Onions: Add sliced onions to the pot and sauté until they become translucent.
4. Add the Chicken: Remove the chicken from the marinade (reserve the marinade) and add it to the pot. Brown the chicken on all sides.
5. Add Marinade: Pour in the reserved marinade along with bay leaves and sugar (if using). Stir to combine.
6. Simmer: Bring the mixture to a boil, then reduce the heat to low. Cover the pot and let it simmer for about 30 minutes. Check occasionally and add water if necessary to prevent burning.
7. Adjust Seasoning: Taste the sauce and adjust with salt and additional sugar if needed.
8. Rest: Once cooked, remove the pot from heat and let it sit for about 10 minutes to allow the flavors to meld.

These steps will guide you in creating a flavorful and tender Chicken Adobo that everyone will love.