Slice cucumber into 1/2" rounds and green pepper into thin strips.
Mix EVOO, red wine vinegar, salt, sugar, oregano, Italian seasoning, mustard powder, and black pepper - ideally allow this to marinate for a few hours to let the spices re-hydrate.
Add vegetables to oil mixture and let sit for 15 minutes.
Slice sub roll from side without cutting through completely.
Spread 2-3 tbsp Hellman's mayo on both sides of roll.
Sprinkle salt and pepper on mayo - ~1/4 tsp or a few pinches.
Layer cotto salami, oiled cucumbers and peppers, optional tomato, and lettuce.
Wrap in parchment paper and slice in half.