2 stalks lemongrass
1/4 cup + 2 teaspoons sugar
2 limes, sliced into 8 lime wedges
Large handful fresh Thai basil (also called pepper basil)
8 ounces white rum
Club soda, as required to top up
Ice, to serve
Lemongrass stalks, trimmed (optional, to use as stir sticks)
First, make the lemongrass simple syrup. Chop the lemongrass stalks into 1-inch pieces, and bruise using a mortar and pestle. Place them in a pot with 1 cup of water and 1/4 cup sugar. Bring to a boil, then reduce the heat and simmer for 2 minutes. Turn off the heat and let the syrup infuse for about 2 hours, or allow to cool and refrigerate for 24 hours.
Strain the syrup, pressing down on the lemongrass stalks to extract maximum flavor. Chill until ready to use. Once the syrup is strained, it will also keep in your fridge for a couple of weeks.
To build each cocktail, arrange 4 cocktail glasses on a work surface and place 1/2 teaspoon sugar in each glass. Add 1 lime slice into each glass along with a handful of Thai basil, and muddle together.
Pour in 2 ounces rum and 2 ounces lemongrass syrup. Top with ice and club soda. Stir and serve.