In a mixing bowl, combine cherry tomatoes, cucumber, red onion, green bell pepper, salami, provolone cheese, black olives, and pepperoncini.

In a separate small bowl, whisk together olive oil, red wine vinegar, Italian seasoning, garlic powder, salt, and black pepper.

Pour the dressing over the salad mixture and toss until well combined.

Slice the sub sandwich bread in half and layer the bottom half with shredded romaine lettuce.

Spoon the salad mixture generously over the lettuce.

Top with the other half of the bread and press down gently.

Optionally, grill the sandwich in a sandwich press or on a grill until golden brown.