Boil the eggs for about 10 minutes until hard-boiled. Cool and peel them.
Trim the green beans and blanch them in boiling water for 3-4 minutes.
Transfer the green beans to an ice bath to stop the cooking process.
Slice the tomatoes and red onion thinly.
In a large salad bowl, layer the mixed greens as a base.
Arrange the sliced tomatoes and green beans on top of the greens.
Place the sliced hard-boiled eggs around the salad.
Add the olives and tuna on top, breaking the tuna into chunks.
In a small bowl, whisk together olive oil, red wine vinegar, salt, and pepper.
Drizzle the dressing over the salad just before serving.