Preheat your oven to 400°.
Slice the focaccia in half and top both halves (cut side) with mozzarella and fontina. Bake until melted - about 4 to 6 mintues.
Meanwhile Make the grinder salad.
In a large mixing bowl, combine mayo, vinegar, garlic, oregano, pepper and red pepper flakes. Whisk to combine.
Add in sliced lettuce, red onion and peperoncini and then toss well to coat.
Once toasted, top the bottom half with ham and prosciutto. Then add salami, soppressata and sandwich pepperoni to the top half. Bake until toasted and the meat heated through - about 6 minutes.
Add sliced tomato, salt and pepper to the bottom half. Top with desired amount of grinder salad and add grated parmesan cheese on top of the grinder salad.
Replace the top halve, slice into fourths and enjoy!
Any leftover grinder salad can be enjoyed with potato chips.