Beetroot is very staining, so it is best to wear disposable gloves when preparing it. First cut off the leaves of the beetroot, then the root end.
Peel red beets generously. Cut into slices and then into cubes. Peel and wash carrots and potatoes and dice them just as roughly. Peel and finely dice the onion.
Heat butter in a large pot. Add beetroot, potatoes, carrots and onion and sauté for 2-3 minutes while stirring.
Pour 1 l water to the vegetables and bring to the boil. Stir in stock. Cover and simmer for about 20 minutes until all vegetables are soft.
In the meantime, peel the horseradish and grate it finely on a kitchen grater. Mix immediately with lemon juice, otherwise it will turn brown. Stir in crème fraiche. Season to taste with salt and pepper.
Finely puree the vegetables in the broth with a hand blender. Season to taste with salt and pepper. Arrange in soup bowls, stir in approx. 1 tsp. horseradish cream fraiche spirally. Served with: farmhouse bread.