Combine the orange juice, elderflower syrup and vanilla pod in a saucepan and heat gently until just boiling. Reduce the heat and simmer gently for 5 minutes. Remove the pan from the heat and leave to cool for 30 minutes.
Put all the fruits in a bowl and mix together gently. Add the syrup mixture and leave to stand for 15 minutes. Serve in bowls with shortbread biscuits.