Trim and portion tuna. Prepare and cook new potatoes and beans and pit olives. Blanch and de-seed tomatoes and cut into petal-shapes if desired. Dice shallots, add vinegar and cover with oil in a pan on the stove, season and allow to cook until darkened by the vinegar.
To serve: split beans and place in a bowl with the potatoes, tomatoes and hard-boiled eggs and olives. Quickly brush slices of bread with olive oil and 'toast' on one side only. Add to salad. Brush tuna with oil and barbecue until pink, season with salt and lemon and place on top of salad. Spoon over dressing and serve.