Cut the cucumbers into thin slices. Slice the wedge of sweet onion into very thin slices. Place in a large bowl.
In a small bowl combine the vinegar, sugar, red wine vinegar, salt and pepper. Taste the dressing--it's easy to adapt it if you want it to be a little sweeter or more tangy.
Pour dressing over veggies and toss to combine. For best results, allow the mixture to marinate for at least an hour before serving.
