Place the beets into a saucepan and fill with just enough water to cover. Bring to a boil, then simmer over medium heat until tender enough to pierce with a fork, about 20 minutes. Drain and remove peels. Run under cold water until cool enough to handle, then grate using the largest setting. Place in a serving bowl.
Mix beets, prunes and walnuts. Pour sunflower oil over the salad and serve.
Note: To make prunes softer cover them with hot water and leave for 15 minutes. Pour water out and then slice.