Oil the french beans in boiling salted water, after having top and tailed them and removed any possible stringy edges. Boil the potatoes, after peeling them, in salted water. Finally boil the aubergines. Hard-boil the eggs, then let them cool. Drain the tuna from the oil, stone the olives and cut the tomatoes into slices.
Place in the centre of a round serving dish, the french beans, surround them with the potatoes cut into slices and arranged in layers and with the aubergines cut into small pieces.
Make a circle of anchovy fillets around the potatoes and the aubergines and, around these, place the slices of tomatoes. Surround these with the slices of three of the hard-boiled eggs, putting a stoned olive on each one.
Cut the remaining egg into quarters, to decorate the french beans with a sort of star, at the centre of which arrange an olive. Put some spoonfuls of oil in a bowl, add the juice of half a lemon, a pinch of salt and a little pepper.
Mix the vinaigrette well, whisking with a fork, then pour it over the vegetables just before taking the dish to the table.