Ingredients:
 
ice, as needed
50ml/1¾fl oz sloe gin
squeeze lemon juice
1 tsp sugar syrup (also sold as gomme syrup)
cream soda, to top up
1 blackberry
1 sprig fresh mint

Method:
 
Fill a highball glass with ice. Pour in the gin, lemon juice and sugar syrup and stir well. Top up with cream soda.
Garnish with a blackberry and a sprig of mint. Serve.