In a mixing bowl, whisk together the balsamic vinegar, honey, minced garlic, olive oil, salt, and black pepper to create the marinade.
Place the chicken thighs in the bowl or a resealable plastic bag and pour half of the marinade over the chicken. Allow it to marinate for at least 15 minutes, or up to 1 hour in the refrigerator for more flavor.
While the chicken is marinating, prepare the vegetables by slicing the zucchini, halving the cherry tomatoes, and dicing the bell pepper.
Heat a large skillet over medium-high heat. Remove the chicken from the marinade and let excess marinade drip off before adding it to the skillet, skin-side down. Sear for about 5 minutes until golden brown, then flip and cook for an additional 5 minutes.
Add the cherry tomatoes, zucchini, and bell pepper around the chicken in the skillet. Pour the remaining marinade over the chicken and vegetables.
Reduce the heat to medium-low, cover, and let it simmer for about 20 minutes, or until the chicken reaches an internal temperature of 165°F (75°C) and the vegetables are tender.
Garnish with fresh basil leaves if desired and serve directly from the pan for a rustic presentation.