Chop or slice the tomatoes into bite-size pieces. If they are very juicy, drain in a colander for a few minutes or gently squeeze some of the seeds and juice out so the dressing does not get watered down. Transfer to a large bowl.
Peel the cucumbers, if desired. I often leave the skin on. Cut in half long ways and, with a spoon, scrape out the seeds. Slice into semi-circles or quarters. Place in the bowl with the tomatoes.
Peel and chop or slice the onion. I use about a quarter of a medium onion, cut into thin slivers.
Stack the leaves from several sprigs of fresh basil on top of one another. Roll the stack of leaves, and slice in thin slivers. I use about a half cup of basil. Again, add more or less according to taste.
Drizzle with approximately one-quarter cup of the dressing. Toss and then add a little more dressing, if needed. Serve with corn on the cob and call it dinner!