1In a large bowl, whisk together the red wine vinegar, white distilled vinegar, oil, sugar, kosher salt, and ground black pepper to create the dressing.
2Peel the cucumbers halfway (stripe peeling) and cut into thick slices. Add to the dressing.
3Slice the yellow onion into rings, separate them, and add to the bowl. Toss to combine.
4Cut the tomatoes into wedges and add to the salad. Season the tomatoes with additional salt to taste.