Place mint, simple syrup, lime juice and Lemongrass-Mint White Balsamic in a wide glass.
With a wooden spoon, muddle mint, simple syrup, lemon juice and balsamic vinegar together to form a good syrup, add ice cubes, then pour Rum and club soda, mix.
Garnish mint leaves and limes.
Bring the water to a simmer in a saucepan set over medium-high heat.
Add the sugar and stir until it completely dissolves.
Remove the pan from the heat. Set aside to cool to room temperature.
Pour the syrup into a clean 1-pint bottle, cap it and refrigerate it until needed.
Makes 1½ cups and keeps two months or longer in the refrigerator.