In a small bowl, combine the vinegar, soy sauce, brown sugar, sambal, and pepper. Whisk to blend thoroughl.
Pat the chicken dry with paper towels. Sprinkle with kosher salt.
Heat the oil in a large skillet over medium heat.
When the oil is hot and shimmering, add the chicken thighs. Cook for about 4 to 5 minutes, or until browned; turn and brown the other side.
Pour the soy sauce mixture over the chicken thighs.
Reduce the heat to medium-low and continue cooking until the liquids are reduced and syrupy, and the chicken is well glazed. Turn the chicken thighs frequently.