Preheat the Oven: Set your oven to 375°F (190°C).

Prepare the Ciabatta: Toss the ciabatta pieces with 1/4 cup olive oil, salt, and pepper in a large bowl. Spread them out on a baking sheet and bake until crispy and golden, about 10-15 minutes. Remove from the oven and allow to cool.

Make the Vinaigrette: In a small bowl, whisk together the red wine vinegar, 1/2 cup olive oil, minced garlic, Dijon mustard, salt, and pepper until well combined and emulsified.

Prepare the Vegetables and Basil: Halve the cherry tomatoes. Thinly slice the red onion. Dice the Persian cucumbers. Finely chop the basil leaves.

Assemble the Salad: In a large mixing bowl, combine the cooled ciabatta, prepared cherry tomatoes, red onion, cucumbers, and basil. Add the mozzarella cheese. Drizzle with the vinaigrette and gently toss to ensure all the ingredients are evenly coated.

Let it Marinate: Allow the salad to rest for about 30 minutes at room temperature to let the bread soak up the dressing and the flavors to meld together.

Serve: Check the seasoning and adjust with more salt and pepper if needed. Drizzle with a little more olive oil, give the salad a final toss, and serve immediately.