Lightly toast the bread under the oven broiler on low.
In a bowl, whisk together the olive oil, vinegar, dijon mustard, and half of the oregano. (Use more if needed but don't drench the bread so it doesn't get soggy)
Drizzle the oil and vinegar inside both halves of the bread. Spread the mayo on the bottom half of the bread. Layer with lettuce, tomato seasoned with salt, pepper, and remaining oregano; turkey, cheese, banana peppers, and roasted peppers.
Cut the loaf into even chunks or wedges and serve with chips and pickles.