dressing serves 4, easily scalable
Boil and chill one egg per serving. Steam for 12 minutes, more detail here.
Blanch green beans in boiling salted water until tender, about 4 minutes, then plunge into ice bath to stop the cooking. Dry and chill until plating.
Boil and chill scrubbed-clean new potatoes, skin intact; about two per serving. About 15 minutes, depending on size.
Add shallot to vinegar and let sit at least 10 minutes to mellow.
Whisk in Dijon mustard, salt, black pepper then drizzle in a stream of olive oil while whisking continuously.
For each serving, arrange lettuce, tuna, halved boiled egg topped with anchovy fillet (optional), green beans, potatoes (halved or quartered), tomatoes, olives, then drizzle with shallot vinaigrette just before serving.