Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
Place the salmon fillets on the prepared baking sheet. Drizzle with olive oil and season with salt and pepper.
Bake the salmon for 12-15 minutes, or until it flakes easily with a fork. Remove from the oven and let it cool slightly.
In a large bowl, combine the mixed salad greens, cherry tomatoes, cucumber, red onion, avocado, and feta cheese.
Flake the cooked salmon into bite-sized pieces and add it to the salad.
Drizzle the balsamic vinaigrette over the salad and toss gently to combine.
Serve immediately or chill in the refrigerator for 15-30 minutes for a refreshing cold salad.