Step 1: Prepare the Vegetables
Wash and slice the cucumbers, tomatoes, and onion.
Place them in a large mixing bowl. Add the chopped parsley if using.
Step 2: Make the Dressing
In a small bowl, whisk together olive oil, vinegar, sugar, oregano, garlic powder, salt, and black pepper until well combined.
Step 3: Combine and Toss
Pour the dressing over the vegetables.
Gently toss everything together until the veggies are evenly coated.
Step 4: Chill and Serve
Cover and refrigerate the salad for at least 20 minutes to let the flavors meld.
Serve cold as a refreshing side dish.