Blanch the wax beans: Plunge the beans into salted boiling water and let cook, 2 minutes. Remove and plunge into ice water to stop the cooking. Dry off completely.
Whisk together the olive oil, vinegar, capers and pepperoncini in a small bowl. Set aside.
Drain the tuna. Leave the tuna in big chunks; do not crumble. Place the lettuce on a platter. Arrange the tuna, onions, wax beans, cherry tomatoes, cucumbers, eggs, roasted peppers and olives on top. Drizzle liberally with the dressing. Garnish with the herbs and season with salt and pepper. Serve.