Add cardamom pod and cucumber wheel to a shaker and muddle. Add remaining ingredients (except for the soda) and fill with ice.
Shake, and double strain into a Collins glass filled with fresh ice.
Top with soda water, leaving room for garnish.Make a small, lengthwise cut in the half celery stalk and place on the rim of the cocktail.
Slap the remaining mint sprigs on the palm of your hand to release the aromas and use them to garnish the drink.