Make the Vinaigrette
In a small bowl, mix together the mustard, lemon juice, Italian seasoning, grated garlic, and salt. Slowly drizzle in the olive oil, while continuing to whisk until the vinaigrette is smooth and the oil has incorporated. Set aside.
Preheat the oven to 425 °F (218 °C). Place the bread on a baking sheet and drizzle the bread with olive oil. Toss the bread in the moil to make sure it's well coated.
Bake the bread for 10-12 minutes, or until golden brown and crisp, turning the pan after about 5 minutes, to ensure it browns evenly.
Let the bread cool completely before putting together the salad.
In a large bowl, mix together the arugula, cucumber, tomatoes, red onion, basil, and capers. Stir in the toasted bread.
Drizzle the vinaigrette over the salad and toss to combine. Add salt and pepper to taste.
Serve chilled or at room temperature.