In a medium bowl, combine all the ingredients for the olive salad. Mix together and transfer to an airtight container. (If needed, pour in a touch more oil to cover.) Cover container and refrigerate overnight.
To Make Sandwiches:
Slice the loaf of bread in half to make a top and bottom for the sandwich; hollow out a touch of the excess bread from the top half to make room for filling.
Brush some of the olive salad juice on both the top and bottom halves of the loaf (go a little heavier on the bottom.) Layer with the salami, ham, mortadella, mozzarella, and Provolone. Top the meats and cheeses with a generous portion of olive salad and add the loaf top.
Serve immediately, or wrap tightly and refrigerate for a few hours (highly recommended); this will allow the flavors to meld and the olive salad to soak into the bread. Let come to room temperature.
Using a serrated bread knife, cut sandwich into wedges/quarters.
Optional: wrap the whole sandwich (before slicing) in foil, place on a large baking sheet, and warm in a 300 degree F oven for about 15 minutes, then unwrap it for about 5 minutes to get it a little crispy.
Nutritional information given is an automatic calculation and can vary based on the exact products you use and any changes you make to the recipe. If these numbers are very important to you, I would recommend calculating them yourself.