Cut the bread in half lengthwise and place it on a baking sheet with the cut side up. Remove most of the inside of the bread, leaving about 1/2-inch of the bread as a shell.
Add half of the provolone to each side of the bread. Place it in the oven until melted, about 5 minutes.
Remove from the oven and layer the ham over one half of the sub, then layer the soppressata on the other side. Next, top the ham with the salami and top the soppressata with the pepperoni.
Place the sub back in the oven to heat the meats through, and toast the bread, for about 5 minutes.
While the sub is baking, prepare the grinder salad by whisking together the mayonnaise, vinegar, garlic, pepper, oregano, chili flakes, and salt until combined. Add the pepperoncini and red onion, and stir around in the dressing until well coated. Then, add the lettuce. Using tongs, toss the lettuce in the dressing to coat, and set aside.
Once the bread is toasted and the meats are heated through, sprinkle the sub with one-quarter of the parmesan cheese. Add tomato slices, then drizzle them with olive oil and sprinkle with salt and pepper to taste.
Add the desired amount of the grinder salad to the top and then top it with the remaining parmesan cheese.
Place the top half of the sandwich over the bottom half, pressing it down gently.
Cut the sandwich into pieces and serve it with more of the grinder salad on the side with chips for dipping!
Notes
The Grider Salad is inspired by a viral TikTok from @ohheyimgray.
I recommend thinly slicing the meat and layering it in a “fluffy” way, as described in the original video. I find it is more enjoyable to eat it that way instead of just layers of meat packed on top of each other.
The grinder salad is definitely the star of this sub. If you don’t like pepperoncini, you can sub with banana peppers or another pickled vegetable. This is what really gives a pop to the salad - so don't omit it!
Leftovers keep well in the fridge tightly wrapped with plastic wrap for up to 2-3 days. The lettuce will get a little soggy, but it is still good. You can eat the leftovers cold, and it is still amazing.
Do not freeze this sandwich. It tends to get all weird when it's thawed.