In a large bowl, combine mayonnaise, white balsamic vinegar, Dijon mustard, minced garlic, oregano, salt, and pepper. Mix well, then add sliced red onion, cucumber, and black olives. Gently fold in the shredded iceberg lettuce.

Preheat your oven to 425°F (220°C). Cut ciabatta rolls in half and layer each half with a slice of white cheddar cheese and a generous portion of sliced turkey. Toast in the oven for 5-10 minutes until the cheese is melted and bread is golden brown.

Once the rolls are toasted, remove from the oven and layer on the sliced avocado. Pile on the grinder salad and serve immediately.