Step 1: Prepare the Bread: Preheat your oven to 375°F (190°C). Cut your day-old sourdough or ciabatta bread into 1-inch cubes. Toss them with 2 tablespoons of olive oil, salt, and pepper on a baking sheet. Spread them in a single layer and bake for 10-15 minutes, or until golden brown and crisp. Set aside to cool.
Step 2: Make the Dressing: In a small bowl, whisk together the red wine vinegar, remaining 1/4 cup olive oil, minced garlic, dried oregano, salt, and black pepper. Taste and adjust seasonings as needed.
Step 3: Prep the Vegetables: In a large bowl, combine the chopped tomatoes, sliced cucumber, thinly sliced red onion, and fresh basil leaves.
Step 4: Combine Bread and Vegetables: Add the cooled toasted bread cubes to the bowl with the vegetables. Pour the dressing over the mixture and toss gently to coat everything evenly. Let it sit for at least 15-20 minutes, allowing the bread to absorb the delicious dressing and juices.
Step 5: Add the Cheeses: Gently fold in the torn fresh mozzarella and shredded provolone cheese into the bread and vegetable mixture.
Step 6: Assemble the Deep Dish: Transfer the entire salad mixture to a deep-dish pie plate or a similar 9-inch round baking dish. Press it down lightly to create a dense, deep-dish-like consistency. Sprinkle the grated Parmesan cheese evenly over the top.
Step 7: Chill and Serve: Cover the salad and refrigerate for at least 30 minutes to allow the flavors to meld. Serve chilled or at room temperature, garnished with extra fresh basil if desired.