To Make Olive Salad: In a medium bowl, combine the green olives, kalamata olives, garlic, cauliflower, capers, celery, carrot, pepperoncini, cocktail onions, celery seed, oregano, basil, black pepper, vinegar, olive oil and canola oil. Mix together and transfer mixture into a glass jar (or other nonreactive container). If needed, pour in more oil to cover. Cover jar or container and refrigerate at least overnight.
To Make Sandwiches: Cut loaves of bread in half horizontally; hollow out some of the excess bread to make room for filling. Spread each piece of bread with equal amounts olive salad, including oil. Layer ‘bottom half’ of each loaf with 1/2 of the salami, ham, mortadella, mozzarella and Provolone. Replace ‘top half’ on each loaf and cut sandwich into quarters.
Serve immediately, or wrap tightly and refrigerate for a few hours; this will allow for the flavors to mingle and the olive salad to soak into the bread.