Arrange the salad greens on a large platter or individual plates.
Arrange the green beans, cherry tomatoes, olives, red onion, hard-boiled eggs, tuna, and capers on top of the greens in a decorative pattern.
In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, minced garlic, salt, and black pepper until well combined.
Drizzle the dressing over the salad just before serving.
Garnish with fresh basil leaves.
Enjoy your meal!