Preheat oven to 375°F (190°C).
Place ciabatta bread halves on a baking sheet, cut side up. Toast in the oven for about 5 minutes or until lightly crispy.
In a mixing bowl, combine olive oil, red wine vinegar, oregano, salt, and black pepper. Whisk until well combined.
Spread the dressing mixture on both halves of the toasted ciabatta bread.
Layer the deli meats, provolone cheese, lettuce, tomato, and red onion on the bottom half of the bread.
Place the top half of the bread over the fillings. Press down gently to secure.
Slice the sandwich into 4 equal parts and serve immediately.