In a bowl large enough to hold all the lettuce add the vinegar and a pinch of salt and pepper. Slowly whisk in the olive oil. Season with more salt and pepper as desired.
Drain the tuna but don't press it dry, leave it coated with a little oil. Toss the lettuce, onions, and artichokes with the dressing and place on a serving platter. Scatter with olives, anchovy, sliced egg, and tuna.