Wash the cucumbers, tomatoes, and onion under cold water. Dice the cucumbers and chop the tomatoes. Thinly slice the onion and combine all ingredients in a large mixing bowl.

Whisk together the vinegar and olive oil in a separate bowl. Add salt, sugar, and cracked pepper, mixing until dissolved. Incorporate water for a lighter dressing if desired.

Pour the dressing over the vegetable mixture and gently toss to combine, ensuring even coating.

Cover the bowl and refrigerate for 15–20 minutes to allow flavors to meld.

Remove from the refrigerator, stir gently, and serve chilled or at room temperature.