Cut the red onion into thin slices.
Peel and cut the cucumber. You can also cut each slice into four pieces, depending on how thick they are.
In a bowl, combine the water with the vinegar and oil.
Add salt and pepper to your liking. Pour the liquid over the mix of cucumber, tomato, and onion.
Mix thoroughly
Put in the refrigerator for up to one hour before serving.
Have fun!
