In a bowl, combine pork strips, vinegar, soy sauce, onions, garlic, bay leaves, and peppercorns. Marinate for about 15 to 20 minutes. Drain meat from marinade, squeezing excess liquid. Reserve marinade and aromatics.
In a pan over medium-high heat, heat oil. Add bell peppers and cook for about 30 seconds. Remove and set aside.
In the pan, add pork and cook, stirring occasionally, until color changes.
Add onions, garlic, peppercorns, and bay leaves (from marinating pork) and cook until softened and pork is lightly browned.
Add reserved marinade and bring to a boil, uncovered and without stirring, for about 4 to 5 minutes.
Add water and bring to a boil.
Lower heat, cover, and simmer for about 25 to 30 minutes or until pork is tender and liquid is reduced.
Add liver, stirring gently to combine, and continue to cook for about 4 to 5 minutes or until liver is cooked through and sauce is thickened.
Add green peas and cook for about 2 to 3 minutes or until heated through.
Add bell peppers and continue to cook for another 1 to 2 minutes or until tender yet crisp. Season with salt to taste. Serve hot.
Allow the vinegar to boil uncovered and undisturbed for a few minutes before adding the soy sauce and water to cook off the strong acid taste.