Slice bread in half and soak each side with vinaigrette. Then build sandwich by layering lettuce, sliced peppers, sliced onion, sliced tomatoes, 2 basil leaves, sliced egg, olives, and then tuna. Then season again with a little more salt and pepper and place top piece of bread on sandwich. Cut in half and serve.
Combine the first 4 ingredients and then whisk in oil. Chill before using.