Thinly slice the cucumbers into rounds about ¼-inch thick. If using regular cucumbers, peel them first and scoop out the seeds with a spoon.
Finely chop the red onion until you have about ¼ cup.
In a medium bowl, whisk together the sour cream, white vinegar, sugar, salt, and black pepper until smooth and well combined.
In a large mixing bowl, combine the sliced cucumbers, chopped red onion, and fresh dill.
Pour the sour cream dressing over the cucumber mixture.
Gently toss everything together until the cucumbers are evenly coated with the dressing.
Cover the bowl and refrigerate for at least 15 minutes to allow the flavors to meld.
Taste and adjust seasoning with additional salt or pepper if needed before serving.
