01 - Preheat a grill or grill pan to medium-high heat.
02 - Brush chicken breasts with 1 tablespoon olive oil and season thoroughly with salt and pepper. Grill for 5–7 minutes per side, or until internal temperature reaches 165°F and juices run clear. Remove from heat and allow to rest for 5 minutes before slicing.
03 - While chicken is cooking, brush peach halves lightly with olive oil. Grill cut-side down for 2–3 minutes until grill marks appear and fruit is slightly softened. Slice each half into wedges.
04 - In a small bowl, whisk remaining olive oil, white wine vinegar, honey, Dijon mustard, chopped mint, and a pinch of salt and pepper until emulsified.
05 - In a large salad bowl, combine spinach leaves, red onion, grilled peach slices, and sliced chicken. Drizzle with mint vinaigrette and toss gently until evenly coated.
06 - Top with crumbled feta cheese and toasted nuts if desired. Serve immediately for optimal freshness.