Preheat your oven to 375°F (190°C). Line a large baking sheet with parchment paper or foil for easy cleanup. If making one big sandwich on a long loaf, lightly spray the foil with cooking spray so nothing sticks.
Slice each hoagie roll horizontally, leaving one long side attached like a hinge so the sandwich stays together. If the rolls are very bready, gently pull out a bit of the soft interior to make room for fillings, leaving enough bread for structure.
In a medium bowl, whisk together the mayonnaise, red wine vinegar, olive oil, Dijon mustard, garlic powder, onion powder, dried oregano, dried basil, red pepper flakes (if using), kosher salt, and black pepper. Taste and adjust seasoning, adding more vinegar for tang or more mayo to soften the acidity.
1/2 cup mayonnaise, 2 tablespoons red wine vinegar, 1 tablespoon extra-virgin olive oil, 1 teaspoon Dijon mustard, 1/4 teaspoon garlic powder, 1/4 teaspoon onion powder, 1/2 teaspoon dried oregano, 1/4 teaspoon dried basil, 1/4 teaspoon crushed red pepper flakes, 1/4 teaspoon kosher salt, 1/4 teaspoon black pepper
Add the shredded iceberg lettuce, shredded romaine, finely chopped red onion, and sliced pepperoncini to the bowl with the dressing. Toss until everything is evenly coated. The salad should look creamy but not soupy; if it seems too loose, add a bit more lettuce. Set aside to let the flavors meld.
2 cups iceberg lettuce, 1/2 cup romaine lettuce, 1/4 cup pepperoncini peppers, 1/4 cup red onion
Place the bottom halves of the hoagie rolls on the prepared baking sheet. Lay 2 slices of provolone on each roll bottom, then sprinkle a generous layer of shredded mozzarella over the provolone. This cheese layer helps keep the bread from getting soggy once the salad is added.
4 large hoagie rolls or sub rolls, 8 slices provolone cheese, 1 cup mozzarella cheese
Build the meat layers on each roll: first add the ham slices, gently folded rather than flat; then layer on the salami; tuck in the pepperoni slices evenly; and, if using, add the turkey or roast beef last. Distribute the meats from end to end so each bite has a bit of everything. If using Parmesan, sprinkle it over the meat layers.
8 oz deli ham, 6 oz Genoa salami, 4 oz pepperoni slices, 6-8 oz deli turkey or roast beef, 2-3 tablespoons Parmesan cheese
Sprinkle the remaining shredded mozzarella over the top of the meat layers to create a cheesy cap that will melt together in the oven.
1 cup mozzarella cheese
Place the sandwiches, still open-faced, in the preheated oven. Bake for 10–12 minutes, or until the cheese is melted and bubbly and the edges of the hoagie rolls are lightly toasted. For extra browning, you can broil for 1–2 minutes at the end, watching closely so they don’t burn.
Remove the tray from the oven and let the sandwiches rest for 2–3 minutes so the cheese can set slightly. Lay 1–2 tomato slices on each sandwich, then spoon a generous layer of the grinder salad over the tomatoes. Add any reserved onion slices, banana peppers, jalapeños, or a light drizzle of Italian dressing if desired.
4-6 slices tomato, 4 slices red onion, 2 cups iceberg lettuce, 1/2 cup romaine lettuce, 1/4 cup pepperoncini peppers, banana peppers or jalapeños, Italian dressing
Gently close the top halves of the rolls over the fillings, pressing lightly so everything holds together. Use a sharp serrated knife to cut each sandwich in half (or into thirds for smaller portions). Serve warm while the cheese is melty and the lettuce is still crisp.