Slice the Italian loaf in half lengthwise and remove a little bread from the center if needed.
In a mixing bowl, combine mayo, red wine vinegar, minced garlic, pepper, oregano, chili flakes, salt, pepperoncini, and red onion.
Fold in shredded iceberg lettuce to coat it well in the grinder dressing.
On the bottom half of the bread, layer provolone, ham, soppressata, salami, and pepperoni evenly.
Add slices of tomato, a drizzle of olive oil, and a sprinkle of salt, pepper, and grated Parmigiano-Reggiano.
Pile the dressed grinder salad on top of the meats and close the sandwich.
Optional: Toast the sandwich in the oven for 3–5 minutes at 375°F until slightly warm and crisp.
Slice and serve immediately.