Start by steaming the eggs (or use your preferred method for hard-boiled eggs) and blanching the green beans. Soak the sliced red onion in cold water if desired to make it less harsh.
To cook the potatoes: Add potatoes to a saucepan or a pot and cover by 2 inches with cold water. Add salt, bring to a boil, and cook until soft but not falling apart.
Make the dressing: In a jar combine the dressing ingredients, and shake until creamy and emulsified. Set aside.
In a large bowl, toss the potatoes with ¼ of the dressing.
To arrange the salad on a serving platter or serving bowl, start by adding the lettuce, followed by the seasoned potatoes, green beans, cherry tomatoes, onions, tuna chunks, olives, and finally the eggs.
Drizzle the salad dressing all over the salad and serve.