Arrange the chicken thighs in one layer in a 6-quart slow cooker.
Add the soy sauce, garlic, bay leaves, peppercorns, brown sugar and water.
Pour the vinegar over the top without stirring, cover and cook on low for 30 minutes.
Turn the thighs once, cover and continue cooking until very tender, 5 1/2 to 6 hours.
Transfer the chicken to a platter and discard the bay leaves.
Cook the sauce uncovered on high until reduced slightly, 12 to 15 minutes, and skim any excess fat.
Spoon the sauce and garlic over the chicken and serve with hot rice.