In a small saucepan, combine the sliced lemongrass, sugar, and water. Stir to combine and bring to a boil over high heat. Once the mixture has been brought to a boil, reduce the heat to low and allow to simmer until the lemongrass is somewhat translucent and the sugar has completely dissolved. Turn off the heat and allow the mixture to steep for about an hour. Strain the syrup into a glass jar with a tightfitting lid. Discard the lemongrass. Store the syrup in the refrigerator until ready to use. Makes about 2 cups of syrup.