Bake the cornbread according to package instructions or your favorite recipe. Allow it to cool completely before cutting into cubes.

In a large mixing bowl, combine the diced tomatoes, bell peppers, sweet corn, green onions, and black olives.

In a separate bowl, whisk together the mayonnaise, apple cider vinegar, oregano, salt, and pepper until smooth.

In a large serving dish, layer half of the cornbread cubes, followed by half of the vegetable mixture, and half of the dressing. Repeat the layers with the remaining ingredients.

Cover the salad and refrigerate for at least 30 minutes before serving to allow the flavors to meld.