5 issues of BBC Good Food for £5
To make the ice cubes, mix the yogurt with a handful of chopped tarragon leaves, then half-fill 2 x 12-cube ice trays (the smallest you have) with the mix. Cover with cling film and freeze overnight.
Put the onions and sugar in a saucepan, cover with a lid, then cook over moderate heat for 10 mins, shaking the pan from time to time. Pour in the wine and vinegar and bubble away until syrupy. Now pour in the stock, add the beetroot and a handful of tarragon leaves. Bring to the boil, then cook for 15 mins.
Blend the soup until smooth, then pass through a sieve into a bowl, pushing as much of the puréed beetroot through as possible. Season with lots of black pepper, then serve hot in shot glasses with a yogurt ice cube on top