Sear the chicken skin-side down in a large skillet over medium-high heat for 3-4 minutes until golden and crispy. Flip once and cook another 2 minutes. Remove chicken and set aside.
2 lbs chicken thighs
Sauté garlic and onion in the same pan over medium heat for 2 minutes until fragrant. Add soy sauce, vinegar, water, bay leaves, and peppercorns. Stir to combine and scrape up any brown bits stuck to the pan.
0.5 cup soy sauce, 0.5 cup vinegar, 1 cup water, 8 cloves garlic, 1 onion, 3 bay leaves, 1 tsp black peppercorns
Return chicken to pan skin-side up and bring liquid to a simmer. Cover with a lid, reduce heat to medium-low, and simmer gently for 30 minutes, keeping the liquid bubbling gently but not boiling.
2 lbs chicken thighs, 0.5 cup soy sauce, 0.5 cup vinegar, 1 cup water, 8 cloves garlic, 1 onion, 3 bay leaves, 1 tsp black peppercorns
Add brown sugar after 30 minutes and stir into the sauce. Remove lid and continue simmering uncovered for 10 minutes until the sauce reduces and thickens to a glossy consistency that coats the back of a spoon.
2 tbsp brown sugar
Check doneness with an instant-read thermometer inserted into the thickest part of the thigh; it should read 165°F (74°C). Let chicken rest in the pan for 5 minutes before serving to allow juices to redistribute.
2 lbs chicken thighs