1) Place beet, carrot and potatoes in a large pot, add water just to cover the vegetables. Bring the pot to a boil and cook the vegetables until tender, about 30-40 minutes. Drain the and let cool till room temperature. Remove skins.
2) Dice the beet and potatoes.
3) Chop the carrot and pickles. Peel and finely chop the onion.
4) Mix all the vegetables in a large bowl. Drizzle the oil over the mixture and toss to coat. Season with salt. (Beet will cover the salad red. If you like other vegetables to retain their color, put the beet on a separate plate, add some oil and toss. Then carefully fold it in with the rest of the salad.)
5) Let cool in refrigerator for at least 30 minutes - 1 hour and serve.