In a large mixing bowl, combine the sliced nectarines, mixed greens, crumbled feta cheese, chopped walnuts, and sliced red onion.

In a separate bowl, whisk together the olive oil, balsamic vinegar, honey, Dijon mustard, salt, and black pepper until well combined.

Drizzle the vinaigrette over the salad and toss gently to combine.

Serve immediately and enjoy!