Pat 2 1/2 to 3 pounds of chicken dry. If desired, combine the chicken with the soy sauce, vinegar, garlic, bay leaves, and peppercorns in a bowl, then marinate for 30 minutes or refrigerate overnight.

Heat the neutral oil in a wide, heavy pot or Dutch oven over medium-high heat. Remove the chicken from the marinade, reserve all the liquid, and brown the chicken skin-side down first for about 3–5 minutes per side, working in batches if needed.

Return all the browned chicken to the pot. Add the reserved marinade and the water or unsalted chicken stock, then add the optional brown sugar.

Bring the liquid to a boil without stirring immediately after adding the vinegar. Let it boil for a few minutes, then reduce the heat to low, partially cover the pot, and simmer for 30–40 minutes, turning the chicken once or twice.

Check that the chicken reaches at least 165°F (74°C) internally; bone-in pieces are often best cooked to about 175–185°F (79–85°C) for tenderness. Remove the lid and simmer for another 5–10 minutes to reduce the sauce.

For a more concentrated sauce, briefly remove the chicken and continue reducing the liquid until glossy, then return the chicken to the pot. Taste and adjust with a little water if the sauce is too strong, or simmer longer if it needs more concentration.

Spoon the chicken and plenty of sauce over cooked white rice. Serve hot, with extra sauce passed at the table.