Place the soy sauce, vinegar, garlic, black peppercorns, and bay leaves in a large, nonreactive sauté pan. Nestle the chicken thighs, skin side down, into the pan.
Bring the liquid to a boil over high heat. Then, cover and simmer over low heat for 20 minutes. Turn the chicken over, cover again, and simmer for an additional 10 minutes.
Uncover the pan and increase the heat to high, bringing the sauce back to a boil. While occasionally turning and basting the chicken, continue boiling the sauce, uncovered, until it reduces by half and thickens slightly, about 5–7 minutes.
Serve the chicken with steamed white rice.
