In a saute pan, heat the olive oil. Season the tuna with salt and pepper. Add the tuna fillet to the pan and sear for 2 to 3 minutes on each side for medium-rare. Remove the tuna and flake the tuna into a mixing bowl. Add the potatoes, green bean, tomatoes, eggs, and black olives. Add the extra virgin olive oil, vinegar and garlic to the bowl and toss well. Season the salad with salt and pepper. Using a sharp knife, slice the head of lettuce in half. Shred the lettuce. Place the lettuce in a mixing bowl and season with olive oil, salt and pepper. Using a small sharp knife, cut out a small pocket in each bread loaf. Fill each bread loaf with the salad. Wrap the sandwich in foil and serve.