Place the potatoes in a large saucepan of water and bring to a boil. Reduce heat, cover, and simmer until fork-tender, about 15 minutes.
Meanwhile, whisk together the chopped herbs, mustard, lemon juice, salt, and olive oil in a medium bowl. Set aside.
Remove the potatoes from the pot and cut them in half when they are cool enough to handle. Arrange the lettuce, potatoes, and green beans on 4 plates. Top each with the salmon, eggs, and olives. Drizzle with the dressing and serve.
Tip: To make perfect hard-cooked eggs (soft whites, no rubbery texture, and no green rings around the yolks) place the eggs in a pot of cold water, then bring it to a boil. Turn off the heat and let the eggs sit in the water, covered, for 15 minutes. Drain, then plunge the eggs into cold water. Peeling the eggs under cold running water makes the shells easier to remove.