Place all the ingredients in a saucepan and heat over a medium heat while stirring until the sugar is dissolved
Bring to the boil, take off the heat and allow to cool
Taste if the cordial needs some extra lemon juice
Serve 1 part cordial to 3 parts bubbly over lots of ice and garnish with fresh mint
Keep any leftover cordial in a clean and airtight container, refrigerated for up to 4 weeks
Makes about 750ml cordial