Makes 4 Cocktails 

Instructions for the Rhubarb puree: Place the rhubarb, water and sugar in a medium saucepan over medium heat. Stir periodically for 5-10 minutes until the rhubarb has broken down into a puree. Place a strainer or sieve over a bowl and pour rhubarb mixture into the strainer. With a spatula or pliable spoon, push the rhubarb through the strainer to release the juice. Allow strained juice to cool. NOTE: pulp is not used in the recipe 

Instructions to make the Cocktail:Mix 1 ounce rhubarb puree with 2 ounces Vodka in a shaker with ice. Shake, strain over fresh ice in a lowball glass. Fill with club soda.