In a small mixing bowl, whisk together balsamic vinegar, honey, and Dijon mustard until well combined.
Gradually stream in the extra virgin olive oil while whisking constantly to emulsify the dressing.
Season the vinaigrette with salt and black pepper and set aside.
In a large salad bowl, combine the mixed baby greens, sliced hearts of palm, halved cherry tomatoes, and diced cucumber.
Drizzle half of the honey balsamic vinaigrette over the salad and toss gently to coat.
Arrange the sliced avocado and red onion on top.
Drizzle the remaining vinaigrette over the top and serve immediately.