Wash the English cucumber and medium tomatoes thoroughly. Slice the cucumber into half-moons and quarter the tomatoes. Thinly slice a brown onion and soak in cold water for about 5 minutes.

In a separate bowl, combine sour cream, salt, and black pepper. Whisk together thoroughly until the mixture is smooth and creamy.

Pour the creamy dressing over the prepped vegetables in a large bowl. Toss the ingredients together gently until evenly coated.

Let the salad rest in the refrigerator for 15-20 minutes before serving to allow the flavors to meld.