1. Bring 5 quarts of water and beef shank to boil in a large pot. Remove all scum. Reduce heat, cover and let simmer for about 40 minutes (until meat is tender).
2. Remove meat and set aside to cool slightly. Then cut it from bone and into bite-size pieces. Return to pot.
3. Place the potatoes in pot.
4. Heat 1 tablespoon of olive oil in a separate skillet over medium heat. Saute onions and carrots in it for about 5 minutes, or until onions become soft and translucent.
5. Add beets to the skillet. Stir in vinegar and 1 tablespoon of tomato sauce or ketchup. Cook vegetables until they are tender, about 10 minutes.
6. Place vegetables in broth, bring the soup to boil. Season with salt and pepper to taste. Reduce heat and simmer a few minutes more.
7. Add parsley flakes, remove the soup from heat. Serve in 5-10 minutes, topped with sour cream.