Place chicken and onion in crock pot; add waterchestnuts.
Pour soy sauce, balsamic vinegar, Worcestershire sauce, bay leaves, bell pepper, garlic, and peppercorns into the crock pot; stir until chicken is entirely coated.
Add brown sugar, cornstarch, and chicken broth; stir again.
Cook on low for 5 to 6 hours.
At end of cooking time, when chicken is cooked, break and shred chicken up a bit; a potato masher works really well for this.
Serve over rice and garnish with chives.