Heat the vegetable oil in a large pot or Dutch oven over medium-high heat.
Add the chicken or pork chunks and cook until browned on all sides. Remove the meat from the pot and set aside.
In the same pot, add the chopped onion and cook until softened, about 5 minutes.
Stir in the minced garlic and cook for another minute.
Return the browned meat to the pot.
Add the soy sauce, vinegar, water, bay leaves, and whole black peppercorns. Stir well to combine.
Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 45 minutes to 1 hour, or until the meat is tender and the flavors have melded. Stir occasionally.
If using, add the sliced green bell pepper and carrots about 10 minutes before the dish is finished cooking.
Adjust seasoning with salt, black pepper, and brown sugar if needed.
Enjoy your meal!