In a large salad bowl, combine the mixed salad greens, cherry tomatoes, cucumber, bell pepper, red onion, and shredded carrots.
If using, sprinkle the crumbled feta cheese over the top of the salad.
In a small bowl, whisk together the olive oil, balsamic vinegar, dried oregano, salt, and pepper until well combined.
Drizzle the dressing over the salad just before serving and toss gently to combine.
Serve immediately for the freshest taste, or chill in the refrigerator for 15-30 minutes to enhance the flavors.