Scrub the potatoes with a soft brush under running water.
Quarter them and drop them into a kettle of cold salted water.
Bring to a boil and cook until tender but still firm, for 8 to 10 minutes after the water reaches a boil.
When the potatoes are done, drain them and place them in a mixing bowl.
Season with salt and pepper to taste, add sour cream to the still-hot potatoes, and toss gently.
Add chopped onion and dill, toss again, and cool to room temperature before refrigerating at least 4 hours.