Preheat your oven to 400°F. Spread the stale bread cubes on a baking sheet and toast in the oven for about 10-15 minutes, or until golden brown and crispy. Remove and let cool.

In a large bowl, combine the chopped tomatoes, cucumber, red onion, bell pepper, and torn basil leaves.

In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, salt, and pepper until well combined.

Add the toasted bread cubes to the vegetable mixture and pour the dressing over the top. Toss gently to combine, ensuring the bread absorbs the flavors.

Let the salad sit for at least 15 minutes before serving to allow the bread to soak up the dressing and juices from the vegetables.