Aunt Peggy's Cucumber, Tomato and Onion Salad

INGREDIENTS

• 1 tablespoon apple cider vinegar
• 2 tablespoons chopped fresh parsley leaves
• 1 pound cucumbers (about 2 cucumbers), peeled and thinly sliced
• 1 pint cherry tomatoes, halved
• Salt and freshly ground black pepper
• 1 tablespoon olive oil
• 1/2 Vidalia onion, very thinly sliced