Chill your coupe or martini glass by filling it with ice water.

Using a jigger, measure out 2 oz. of gin, 1 oz. of elderflower liqueur, 1 oz. of fresh lemon juice, and 1 oz. of lavender syrup.

Fill a cocktail shaker with ice to the top.

Add the measured gin, elderflower liqueur, lemon juice, and lavender syrup into the shaker.

Secure the lid on the shaker and shake vigorously for about 15 seconds.

Discard the ice water from your glass and strain the mixture into it.

Gently pour a splash of club soda on top of the cocktail.

Add a sprig of lavender for garnish.