Pat chicken thighs completely dry with paper towels and season generously with salt and pepper on all sides.

Heat vegetable oil in a large, heavy-bottomed skillet or Dutch oven over medium-high heat until shimmering.

Brown chicken thighs skin-side down first, about 4-5 minutes per side, until golden brown and crispy. Remove chicken to a plate and set aside.

Reduce heat to medium and add minced garlic to the same pan. Cook for 30 seconds until fragrant, stirring constantly to prevent burning.

Add soy sauce, rice vinegar, brown sugar, bay leaves, and black peppercorns to the pan. Stir to combine and bring to a simmer.

Return chicken thighs to the pan skin-side up, along with any accumulated juices. Add water if needed to partially cover the chicken.

Bring to a gentle simmer, then reduce heat to medium-low. Cover partially and cook for 20-25 minutes, until chicken is tender and cooked through (internal temperature of 165°F).

Remove lid and increase heat to medium-high. Cook for 5-8 minutes more, turning chicken once, until sauce reduces and becomes glossy.

Remove bay leaves and discard. Taste sauce and adjust seasoning if needed – add more soy sauce for saltiness or vinegar for tang.

Serve immediately over steamed rice, spooning the sauce over the chicken and rice. Garnish with sliced green onions.