Preheat your oven to 400°F (200°C).

Pat the chicken thighs dry using paper towels and season generously with salt and pepper.

In a small bowl, whisk together balsamic vinegar, olive oil, minced garlic, dried oregano, salt, and black pepper.

Heat a tablespoon of olive oil in an oven-safe skillet over medium-high heat. Sear chicken thighs skin-side down for about 5 minutes until golden brown.

Arrange halved cherry tomatoes, chopped bell pepper, and sliced onion around the chicken in the skillet.

Drizzle the balsamic marinade over the chicken and vegetables, ensuring everything is coated.

Transfer the skillet to the oven and bake for 25-30 minutes until chicken reaches an internal temperature of 165°F (74°C).

Remove from oven and let chicken rest for 5-10 minutes before serving.

Garnish with fresh basil leaves before serving.