Adjust an oven rack to the middle position and heat the oven to 400°F. Toss the bread cubes with the olive oil on a rimmed baking sheet and bake until golden brown and crisp, about 10 to 15 minutes, tossing halfway through for even browning.

Whisk the olive oil, vinegar, garlic, salt, and pepper in a large bowl until well combined.

Add the tomatoes, cucumber, red onion, and olives to the bowl with the vinaigrette. Toss to coat thoroughly and let the mixture sit for about 15 minutes — the salt will draw out the tomato juices to create a flavorful liquid for the bread to absorb.

Add the toasted bread and basil to the vegetable mixture and toss well. Let the salad stand for 10 to 20 minutes, which allows the bread to soak up the juices until it is tender but still has some structure.

Gently fold in the feta cheese just before serving so it stays in distinct, creamy crumbles rather than dissolving into the dressing.

Serve at room temperature, ensuring each portion has a mix of the softened bread and crisp vegetables.