01 - Wash and thinly slice the cucumbers and onion, then halve the cherry or grape tomatoes.
02 - In a mixing bowl, vigorously whisk together the vinegar, olive oil, minced garlic, salt, pepper, and optional red pepper flakes until well combined.
03 - Transfer the sliced cucumbers, tomatoes, and onions to a large bowl. Pour the vinaigrette over the vegetables and gently toss until evenly coated.
04 - Cover the bowl and refrigerate for at least 30 minutes, allowing the flavors to develop. For optimal taste, chill for several hours or overnight.
05 - Toss the salad to redistribute the marinade, then garnish with chopped fresh parsley or dill before serving.