01 - Fill a cocktail shaker with ice cubes to chill the vessel
02 - Pour Irish whiskey, green crème de menthe, fresh lemon juice, and simple syrup into the shaker
03 - Shake vigorously for approximately 15 seconds until the mixture is thoroughly chilled
04 - Strain into a chilled cocktail glass
05 - Add a lemon twist or fresh mint sprig. Serve immediately while cold