Prepare the Teriyaki Marinade: In a small mixing bowl, whisk together brown sugar, soy sauce, vinegar, minced garlic, and black pepper until the sugar dissolves and a smooth marinade forms. This blend will add a perfect balance of sweet and savory notes to your chicken.
Marinate the Chicken: Place the chicken thighs into a large, sealable plastic bag or shallow dish. Pour the marinade over the chicken, seal or cover tightly, and massage gently to coat each piece thoroughly. Refrigerate for at least 30 minutes or up to 2 hours for deeper flavor infusion.
Start Cooking in a Skillet: Preheat a large nonstick or cast-iron skillet over medium heat. Using tongs, transfer the marinated chicken thighs to the pan, discarding any leftover marinade to avoid cross-contamination. Cover with a lid and cook undisturbed for 8 minutes, allowing the meat to sear and release its natural juices.
Flip and Glaze the Chicken: Remove the lid, carefully flip each thigh, and continue cooking for another 5 minutes, or until the internal temperature reaches 165°F (74°C). As the chicken cooks, the remaining sauce will thicken into a glossy glaze. Use your tongs to turn and coat the chicken evenly in the glaze before serving.
