1 cucumber, sliced thin
1/4 red onion, sliced thin
2 teaspoons apple cider vinegar
1/2 cup sour cream
1 tablespoon dill
1/4 teaspoon salt
1/4 teaspoon black pepper
1 teaspoon sugar
Mix all of the seasonings. Pour over a bowl containing the cucumbers, onions, and tomatoes. Refrigerate at least 2 hours before eating.
This also works with yellow onion.