Place 10 fresh blueberries in a mixing glass or shaker. Add the simple syrup and gently muddle until the berries are broken and release their juice but not pulverized (about 6–8 gentle presses).

Build the cocktail

Add the gin, blueberry liqueur, and fresh lemon juice to the muddled blueberries. Add plenty of ice to the shaker (or mixing glass) and shake vigorously for 10–12 seconds to chill and integrate flavors.

Strain

Double-strain the shaken mixture into a chilled 6–8 oz wine glass or rocks glass filled with fresh ice using a fine-mesh strainer to remove blueberry solids (this yields a smooth spritz base).

Top with bubbles

Gently pour the sparkling wine over the strained mixture, followed by the chilled soda water. Stir once gently with a bar spoon to combine without flattening the bubbles.

Blueberry muddle & garnish

Finish and garnish

Skewer the remaining 2 blueberries on a cocktail pick and place on top of the ice. Express the lemon peel over the glass to release oils, rub it around the rim, then drop it into the drink. Add a mint sprig if desired for aroma.

Serve immediately and enjoy. The finished drink should total about 5 oz of liquid (excluding ice) and present a pale purple hue with a lively effervescence.