Gently wash produce under cool running water, pat dry, and prepare as directed.
Place the cucumbers in a serving bowl and add the salt. Let sit for 5 minutes, then pour off any water that collects.
Stir the vinegar into the sour cream in a small bowl.
Add the sour cream mixture to the cucumbers, along with the onion and the black pepper. Stir to combine.
Refrigerate for at least 1 hour before serving.