Wash the brambles and place them in a bowl or large jar.
Pour over the sugar and stir it in well, crushing the brambles a little to get them started.
Cover the bowl or jar with clingfilm or an eco friendly alternative, and place in the fridge for 24 – 48 hours.
Stir the berries every 6-8 hours to make sure all the sugar gets dissolved.
Strain the berry mixture through a fine sieve, catching the sirup in another bowl.
Measure 500ml of apple cider vinegar in to a sterilised bottle.
Pour in the berry sirup and seal the bottle tightly.
Store in the fridge, and leave for at least 72 hours before tasting.
To serve, measure out ca. 2 tablespoons of shrub sirup in to a glass and top up with sparkling water.