In a glass measuring cup whisk together vinegar, soy sauce, brown sugar, and peppercorns. Set aside.
Heat oil in a large pot over medium-high heat. Dab skin on chicken dry with paper towels then add 3 thighs to pot, skin side down. Let sear until golden brown on bottom, about 4 - 6 minutes.
Transfer chicken to a plate then repeat with remaining 3 thighs, while adding garlic to pan with chicken during the last 30 seconds to saute briefly to remove harsh bite.
Remove pan from heat and carefully pour in vinegar mixture, return 3 chicken pieces to the pot, skin side down. Nestle in bay leaves. Return to heat, bring sauce just to a boil then reduce heat to low, cover and simmer 20 minutes.
Flip chicken to opposite side, continue to simmer, uncovered, until chicken is cooked through and about 20 minutes longer.
Remove bay leaves. Serve chicken warm over rice with some of the sauce spooned over**.