Start by preparing the ingredients. Wash the cherry tomatoes and cut them in half. Peel the hard-boiled egg and cut it into large pieces. Drain the can of tuna well. Whisk the olive oil and red wine vinegar together in a small bowl to make a quick dressing.
Clean the green beans by trimming the ends. Bring a pan of water to a boil and blanch the green beans for four minutes until tender-crisp. Drain them immediately in a colander and rinse them briefly under cold running water so they don't continue cooking and stay nice and crisp.
Take a large, deep plate for plating the dish. Arrange the cooled green beans, halved cherry tomatoes, black olives and egg pieces neatly around the edge of the plate. Scoop the drained tuna in the center among these ingredients.
Spoon the olive oil and red wine vinegar dressing evenly over the vegetables, egg and tuna. Season finally with pepper and serve the plate immediately.