In a large pot of boiling salted water, cook potatoes until fork tender.
Drain, cool, peel and cut into 1/2-inch cubes. if using fresh beets, prepare in the same manner, reserving 1/2 cup beet juice.
In a large bowl, mix reserved beet juice, vinegar and sugar. Pour over salad. toss gently.
Season to taste with salt and white pepper. Add more vinegar if tangier flavor is desired.
Cover and refrigerate at least 3 hours hours or overnight.
To serve, mound salad in a large platter. garnish top center with capers.
Sprinkle chopped egg and parsley in rings around capers.
Serve with sour cream on the side, if desired.