Use the tip of a small, sharp knife to score the vanilla pod lengthways through to the centre. Put the measurement water and sugar in a saucepan and heat gently until the sugar has dissolved. Add the vanilla pod and chilli and heat gently for a further 2 minutes. Remove the pan from the heat and leave to cool while you prepare the fruit.
Remove the peel from the clementines and slice the flesh. Stone and slice the peaches. Cut the melon flesh into small chunks, removing and discarding the skin.
Put the prepared fruit and blueberries into a serving dish and mix together, then pour over the warm syrup, Serve immediately decorated with the chilli and half a vanilla pod (discard just before eating), or cover and chill until ready to serve.