Bring 100 ml of water and the caster sugar to the boil. Stir until the sugar crystals have dissolved, then allow the syrup to cool completely.
Remove some of the gold coloured leaves from the physalis, but leave four. Then wash the berries.
Squeeze the limes and oranges. Blend the berries with the juice, gin and sugar syrup in the blender until completely smooth. Fill the cocktail glasses with crushed ice and strain the cocktail over the glasses. Decorate with the physalis with leaves, a pansy and a few leaves of cress.
