1Boil eggs: lower into boiling water, cook exactly 10 minutes for hard boiled, transfer immediately to ice water for 5 minutes then peel and slice in half.
2Blanch green beans: bring salted water to a boil, add trimmed beans and cook exactly 3 minutes until bright green and tender-crisp. Drain and immediately plunge into ice water to stop cooking and preserve the vibrant green color.
3Make dressing: whisk olive oil, lemon juice, Dijon mustard, garlic, salt, and pepper until emulsified.
4Arrange salad leaves on a wide plate or in a container. Drain tuna completely and flake into chunks in the center.
5Arrange eggs, green beans, tomatoes, olives, capers, and red onion around the tuna in separate sections. Drizzle dressing over everything, top with fresh parsley.