Season the chicken breasts with salt and pepper on both sides.
Heat olive oil in a large pan over medium heat. Add chicken and sear for 5-6 minutes on each side until golden and cooked through. Transfer to a plate.
In the same pan, add cherry tomatoes, green beans, and red onion. Cook for about 4-5 minutes until slightly softened.
Add garlic and stir for 1 minute until fragrant.
Whisk together balsamic vinegar, honey, Dijon mustard, and oregano in a small bowl. Pour into the pan with the vegetables.
Return chicken to the pan, coating with the balsamic glaze. Simmer for 3-4 minutes until sauce thickens slightly.
Sprinkle with fresh basil before serving, if desired.