Add the vodka, rhubarb simple syrup, and lemon juice to a cocktail shaker and fill with ice.
Shake vigorously, and then strain into a glass filled with fresh ice.
Top with club soda or sparkling wine, and garnish with lemon wheel.
Notes
Non-Alcoholic Rhubarb Mocktail: This Rhubarb cocktail can easily be made non-alcoholic. Just omit the vodka, add a little more syrup (around 1/2 additional oz), and top with club soda or lemon-flavored sparkling water.