There are numerous recipes for lemon balm lemonade, and I have an old English recipe myself that I make regularly - but, if you find that it is sometimes a little "light" on the lemon flavour, add some lemon verbena for a super charged lemon kick! I have made this several times now and it is so refreshing and zingy, perfect for a hot summer's day. Once the syrup is made, it lasts for several weeks in the fridge, or several months in a cool dark place if you add the optional citric and tartaric acid. Serve with cold sparkling water and slices of lemon and a sprig of either lemon balm or lemon verbena.