Prepare Kumquats: Wash and halve 4 fresh kumquats.
Muddle the Kumquats: In a cocktail shaker, gently muddle the halved kumquats to release their juice and oils.
Add Ingredients: Add 1 1/2 oz gin, 3/4 oz St. Germain liqueur, and 1/2 oz simple syrup to the shaker.
Shake and Mix: Fill the shaker with ice and shake gently to combine all ingredients.
Finish the Cocktail: Strain the mixture into a chilled glass, and top with 3 oz of club soda for a bubbly finish.
Garnish: Add a twist of kumquat peel or fresh mint leaves for garnish. Serve immediately.