1 Place the beetroot, hot stock and 2 tbsp vinegar in a pot and simmer for 30 minutes on a low heat.
2 Remove half the beetroot from the pot and puree the rest. Return the beetroot to the soup and season with salt and ground black pepper. Leave to cool and place in the fridge to cool completely.
3 Stir the buttermilk and the mascarpone into the soup and add the radishes, gherkins and beetroot leaves. Season carefully with a little vinegar and add a little more stock if necessary.
4 Transfer to deep plates and garnish with half an egg and the dill.