01 - Whisk together olive oil, balsamic vinegar, honey, minced garlic, salt, and pepper in a small bowl. Reserve half of this mixture for the salad dressing.
02 - Place chicken breasts in a shallow dish and pour half of the marinade over them, turning to coat evenly. Allow to marinate for at least 15 minutes, or refrigerate for up to 2 hours for deeper flavor.
03 - Heat a grill or grill pan over medium-high heat. Lightly brush peach halves with olive oil to prevent sticking.
04 - Cook marinated chicken for 6-7 minutes per side until internal temperature reaches 165°F and juices run clear. Transfer to a cutting board and let rest for 5 minutes before slicing into strips.
05 - Place peach halves cut-side down on the hot grill for 2-3 minutes until distinct grill marks appear and fruit begins to soften. Remove and slice each half into wedges.
06 - In a large serving bowl, combine arugula or mixed greens, cherry tomatoes, red onion slices, grilled peach wedges, and torn basil leaves.
07 - Drizzle the reserved dressing over the salad and toss gently to coat. Arrange sliced grilled chicken on top and sprinkle with crumbled feta cheese if desired. Serve immediately while chicken and peaches are still warm.