Combine the cut corn, spinach, onion, cucumbers/cucamelons, and other vegetables you're adding in a mixing bowl. Save the tomatoes though & don't add them in quite yet.
Stir 1 tablespoon of dressing into the combined vegetables and then taste test. If desired, add another 1/2 to 1 additional tablespoon of dressing, to taste.
Finally, gently stir in the tomatoes and your salad is ready to serve!
This salad is best served fresh, the same day, but leftovers can be refrigerated and eaten the next day.