-Whisk water, vinegar, oil, sugar, salt, and pepper together in a large bowl until smooth; add cucumbers, tomatoes, and onion and stir to coat.
-Cover bowl with plastic wrap; refrigerate at least 2 hours.
-Whisk water, vinegar, oil, sugar, salt, and pepper together in a large bowl until smooth; add cucumbers, tomatoes, and onion and stir to coat.
-Cover bowl with plastic wrap; refrigerate at least 2 hours.