Yields: 2 servings
To a small saucepan over medium heat, add the sugar and water. Bring to a simmer and stir until sugar completely dissolves (on my stove this only takes about 60 seconds). Remove from heat and set aside to cool. This is your simple syrup.
Combine together the grapefruit juice and 1/4 cup of the simple syrup. Stir to combine. Add 1 cup of club soda. Fill two glasses with ice and pour the soda mixture over the ice. Serve.