Soak the onions in ice-cold water for about 15 minutes. This helps in cutting down on the raw, sharp taste in onions and adds crispness.
Cut the bread into halves, lengthwise. Dig up a well-like structure in the bottom half.
In the well, drizzle two tablespoons of each of the vinegar and extra-virgin olive oil. Add pepper and salt according to taste.
Layer the meat and cheese as per your liking on the bottom half of your bread.
Drain the soaked onions in water. Pat the onions dry to ensure that you get rid of all water content.
Top the meat and cheese layers with lettuce, tomatoes, pepperoncini (optional), and onion.
Drizzle two tablespoons each of olive oil and vinegar.
Garnish with some oregano, and sprinkle some salt & pepper to taste.
On top of this, drizzle one tablespoon of olive oil and vinegar.
Wrapping up, garnish the sandwich or the upper half of the bread with remaining dried oregano for added taste.
Cut into four pieces (optional) and serve fresh!