Beetroot Soup

Our answer

We suspect that the recipe you may be thinking of is the Spiced Pink Soup which appeared in Nigella's TV show Forever Summer and is also in the Forever Summer book, on p.22. The beetroots are roasted in a foil package to intensify their earthy, sweet flavour, then cooled and peeled before using.

The soup itself is served chilled as it is a summer soup. If you did want to serve it warm then you would need to heat it through gently without the sour cream, then serve in bowls with dollops of cream swirled through (if you heat the soup with the cream added already then the cream will turn grainy).