Whisk together all the ingredients in a medium size bowl until combined. Chill it until it is ready to be served. In a large pot of boiling salted water, add in the potatoes and cook.
Next, add in the green beans to the boiling salted water and cook until al dente. Remove them and shock in an ice bath immediately. Remove from the water and chill until ready to serve.
Season the tuna on all sides with salt and pepper and set on a plate. Heat a grill pan over high heat and add in the olive oil. Add in the tuna and turn the heat down to medium-high and cook it.
Place the romaine lettuce in a bowl and evenly add on the cooked red potatoes, green beans, cooked tuna, tomatoes, hard boiled eggs, artichokes, red onions, olives, and anchovies.