Step 1.
- In a shaker, muddle the blackberries gently to release their juices.
Step 2.
- Add the gin, elderflower liqueur, and lemon juice to the shaker with the muddled blackberries.
Step 3.
- Fill the shaker with ice and shake well until chilled.
Step 4.
- Strain the mixture into a Collins glass filled with ice.
Step 5.
- Top with soda water and stir gently to combine.
Step 6.
- Garnish with fresh blackberries and a sprig of mint.