Preheat the oven to 300 degrees. Split the sub rolls and lay them onto a baking sheet. Spread about 1 tablespoon of sweet balsamic onto one side of the inside of the sub roll, and about 1 tablespoon of basil pesto on the other side.
Fill each sub roll with even amounts of the salami, pepperoni, ham, and 2 slices of mozzarella cheese. Sprinkle oregano over the cheese. Place into the oven and bake at 300 degrees for 10 minutes (or longer if you want them toasted more).
Remove from the oven. Top the subs with 2 slices of tomato, 2 slices of onion, pepperoncini, black olives, and lettuce.