Place the bread cubes in a large bowl. Drizzle the olive oil over the bread and sprinkle with seasoning and salt. Toss to combine. Arrange the bread cubes on a baking sheet and bake for 10 minutes, stirring halfway through. Remove from the oven and let cool.
In a large bowl, combine the remaining salad ingredients (cucumber through olives).
In a small bowl, mix together the lemon juice, zest, oregano and mustard. While whisking constantly, drizzle in the olive oil until thoroughly blended. Pour the dressing over the salad and toss.
Add the bread cubes to the salad and toss to coat. Allow the salad to sit at room temperature for 10 to 15 minutes before serving.