Cut a notch in a lemon wedge, then run the lemon around the rim of a martini glass. Dip the edge of the rim into a plate of superfine sugar.
Make the lemon twist.
Place the vodka, Cointreau, lemon juice, and simple syrup in a cocktail shaker, fill it with ice, and shake until cold.
Strain the drink into the glass with the sugared rim. Garnish with the lemon twist.