Bring the sugar and water to a boil in a small saucepan over high heat and simmer until reduced by 1/4. Add the parsley and let steep for at least 30 minutes, then strain and refrigerate the syrup until ready to use.
To make the cocktail, pour 1/2 cup parsley syrup with the vodka, gin, lemon juice in a shaker with ice. Shake vigorously. Strain the cocktail into pint glasses filled to the brim with ice cubes.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.