In a bowl, whisk together mayo, olive oil, red wine vinegar, garlic powder, Italian seasoning, salt, and pepper until well combined. Set the dressing aside to let the flavors meld while you prepare the rest of the sandwich.
Slice the tomato and pat it dry with a paper towel to prevent the sandwich from becoming soggy.
Thinly slice the red onion and shred the romaine lettuce.
Slice the sub rolls in half lengthwise, removing some bread inside. Spread with mayo
Start with salami, followed by pepperoni, and then ham.
Place a slice of provolone on top of the meats.
Add the tomato slices, red onion, and shredded lettuce.
Drizzle the prepared sub sandwich dressing generously over the vegetables for a tangy, zesty finish.
Gently close the sandwich, pressing lightly to hold everything together.
Slice the hoagie in half if desired, and serve immediately.