Chop the onions. Peel and dice the potatoes. Dice the beetroot as well.
Heat the oil and sauté the onions in it. Add the beetroot and potatoes and sauté for about 2 minutes. Add the broth and bring to the boil. Let simmer for 15-20 minutes.
Puree the soup and pour it through a sieve. Pour in the beetroot juice and bring to the boil again. Add the horseradish and buttermilk. Season to taste with salt and pepper.
Cut the chives into rolls and chop the dill. Garnish the soup with it.