Bring 1 cup of water to a boil in a small saucepan
Once the water is boiling, whisk in 1 cup of granulated sugar
Continue whisking until the sugar is completely dissolved
Remove the simple syrup from the heat and whisk in the fresh grapefruit juice
Allow the grapefruit simple syrup to cool to room temperature
Fill a glass half full with ice
Add enough grapefruit simple syrup to come half way up the side of the glass
Fill the rest of the glass with sparkling water
Add a splash of grenadine syrup (optional)
Garnish with grapefruit wedges and fresh mint leaves