Bring the sugar, cloves, lemongrass stalks, and sliced ginger to a boil in a large pot.
Let the mixture simmer for ten minutes, then add 500 ml of water.
Add the lime juice and peel. Cover the pot and let it infuse for a day to allow the flavors to meld well.
Strain the mixture thoroughly and add the elderflower petals. Make sure to remove the stems.
Pour the syrup mixture into a large bottle and add the lemongrass stalks for an extra touch.
When you're ready to serve, dilute the syrup with cold sparkling water to taste, or use it as a base for other drinks.
Tips
Do you suffer from crystallization on the bottom of your bottle? Add a few drops of tartaric acid, available at the pharmacy. And don't forget to add some ice cubes in the hot summer months!