Lemon slices and additional blueberries, for garnish
Instructions:
In a small saucepan, combine the blueberries, sugar, and water. Cook over medium heat, stirring occasionally, until the blueberries are soft and the sugar has dissolved, about 5 minutes.
Remove the saucepan from the heat and allow the blueberry mixture to cool for about 10 minutes.
Once cooled, use a fine-mesh strainer to strain the blueberry mixture into a bowl, pressing on the solids to extract as much juice as possible. Discard the solids and set the blueberry syrup aside.
In a cocktail shaker, combine 1 ounce of the blueberry syrup, vodka or gin (if using), and lemon juice. Fill the shaker with ice and shake well until chilled, about 15-20 seconds.
Fill a glass with ice and strain the cocktail mixture into the glass.
Top off the glass with sparkling water and give it a gentle stir to mix.
Garnish with lemon slices and additional blueberries, if desired.
