Place the potato pieces in a large pot. Cover with cold water and bring the water to a boil. Then, reduce heat to low and simmer for 20-25 minutes, until tender. Drain and place in a large bowl.

Slice the one hard-boiled egg and set it aside.

Chop the remaining four of the hard-boiled eggs and place them in a bowl with the cooked potatoes. Add the chopped celery, chopped dill pickles, and sliced green onions.

In a small bowl, combine the mayonnaise, sour cream, mustard, vinegar, salt, sugar, and black pepper.

Add the dressing to the ingredients in the bowl and stir to coat.

Top with the sliced hard-boiled egg and sprinkle with paprika. Cover and refrigerate for 2 hours before serving.