One summer in Collinsville the garden was overflowing with cherry tomatoes and cucumbers, so we ate this salad for lunch every other day.
In a small bowl, combine the vinegar, salt, pepper, and olive oil to make the vinaigrette.
Wash and halve your cherry tomatoes. Slice a cucumber lengthwise before using a spoon to scoop most of the seeds out and slicing cross-wise. Slice the red onion as thin as you can get it. It may be worth tossing everything into a salad spinner just to get the extra tomato juice out.
Toss the veggies in a large salad bowl with the vinaigrette, taste for salt and add any if it needs it. Crumble the feta into large chunks or cut into cubes to add to the salad. Lightly toss and serve on a hot summer day.
The exact amounts of each veggie isn't really important here but you need a far amount of cherry tomatoes and at least 1 whole cucumber (or "big damos" as John used to say back then).