Put chicken in a bowl . Combine vinegar and 1 tablespoon of the chopped garlic. Pour over chicken and turn to coat. Marinate in the fridge 30 mins. Remove chicken from the marinade, allowing excess to drip back into the bowl and transfer chicken to a clean plate. Reserve the marinade.
Heat oil over medium heat in a large heavy pot with a lid. Pat chicken lightly to dry. Brown in batches starting skin side down for 3-4 minutes. Turn and brown for just a minute on the other side. Transfer to a clean plate. Repeat with all the chicken. Pour out all but 2 tablespoons fat from the pot. Set the heat to medium-low, add onions and the rest of the garlic to the pot and sauté, stirring occasionally, for about 10 mintutes, until the onions are softened.
Return the chicken to the pot along with any accumulated juices, vinegar-garlic marinade, soy sauce, fish sauce, black pepper, bay leaves and ¼ cup of water. Toss chicken with onions and sauce to coat. Bring to a boil,then simmer at a low steady simmer for 30 minutes.Skim most of the fat.
Toss chicken to coat with sauce. Continue to simmer gently for 30 more minutes, until the chicken is tender and the sauce is a rich brown color. Serve over garlic rice.