Soften the gelatine in iced cold water for 10 minutes. Bring the cream, egg yolk and sugar to 86°C in a Thermomix. Add the gelatine, followed by the vinegar and beetroot. Blend to a smooth purée. Pass through a chinoise and pour into a piping bag. Leave to set in the fridge.
When set, pipe the mixture onto sheets of clingfilm 30cm long. Roll into cylinders 3cm in diameter and freeze. Cu