01 - Combine chicken, soy sauce, vinegar, garlic, bay leaves, peppercorns, and brown sugar in a large bowl. Toss to coat thoroughly. Marinate for at least 30 minutes, or refrigerate overnight for deeper flavor penetration.
02 - Remove chicken from marinade, reserving the liquid. Pat each piece completely dry with paper towels to ensure proper browning.
03 - Heat oil in a large, deep skillet or Dutch oven over medium-high heat. Add chicken pieces skin-side down and sear until golden brown, 2–3 minutes per side. Work in batches if necessary to avoid overcrowding.
04 - Add sliced onion to the pan and sauté for 2 minutes until slightly softened and fragrant.
05 - Pour reserved marinade and water into the pan. Add potatoes if using. Bring mixture to a gentle simmer.
06 - Cover and reduce heat to low. Cook for 25–30 minutes, stirring occasionally, until chicken is tender and cooked through.
07 - Uncover and simmer for an additional 10–15 minutes to reduce the sauce until it reaches desired consistency. Remove and discard bay leaves.
08 - Adjust seasoning to taste. Serve immediately over steamed rice, garnished with chopped scallions or fried garlic if desired.