Ingredients (Serves 4)
For the compote
First make the panna cottas. Put the gelatine into a bowl, cover with cold water and leave until floppy. Heat the milk. Slit the vanilla pod, scrape out the sticky seeds with a sharp knife and add to the milk together with the pod and the honey. Bring to the boil and remove from the heat when it starts to bubble around the sides of the pan.
Squeeze any excess water from the gelatine sheets and stir into the milk until dissolved. Beat in the yoghurt until smooth and pour through a sieve into a bowl. Cool, then chill in the fridge, stirring every 30 minutes, until it begins to set.
Decant into four lightly oiled, 125ml/41⁄2fl oz ramekins. Chill until completely set. Meanwhile, make the compote. Trim the rhubarb and cut into 3cm/11⁄4in lengths. Heat the fruit sugar or caster sugar with the water in a medium saucepan and stir until dissolved, then add the rhubarb and bring to the boil. Simmer gently for about 5 minutes. Remove and leave to cool.
When cooled, run a table knife carefully around the pannacottas, lightly shake on to small dessert plates and serve with the compote, sprinkled with the pistachios.