In a large bowl, combine the diced cucumbers, diced tomatoes, and sliced red onion.

Add the chopped parsley and mint to the bowl with the vegetables.

In a small mixing bowl, whisk together the olive oil, lemon juice, salt, black pepper, and garlic powder until well combined.

Pour the dressing over the cucumber and tomato mixture, and gently toss until everything is evenly coated.

Let the salad sit for about 10 minutes to allow the flavors to meld before serving.