Ingredients

• 1/4 cup balsamic vinegar

• 2 tablespoons extra-virgin olive oil

• 2 tablespoons honey

• 1 tablespoon Dijon mustard

• 1 1/2 teaspoons kosher salt

• 1/2 teaspoon garlic powder

• 1/2 teaspoon dried oregano

• 1/2 teaspoon black pepper, plus more for garnish

• 4 small (6- to 8-ounces each) boneless, skinless chicken breasts, patted dry

• 1 large red onion, peeled and cut into 1-inch wedges

• 4 cups cherry or grape tomatoes

• 8 ounces feta cheese packed in brine

• Chopped fresh basil leaves, for garnish