
Elderflower cordial is a non-alcoholic elderflower infusion, sweetened and soured with citric acid or lemon, so it is tart as well as sweet.
It brings both the sugar and the elderflower, so a drink built on it often needs little or no other syrup. Overdone, elderflower turns soapy, and a short drink reaches that point sooner than a long one. Gin, cucumber and lemon are its classic partners.
Cut it with water: about 9 ml of syrup plus 6 ml of water for every 15 ml of cordial. The balance mostly holds. If it tastes flat, add a few drops of lemon juice.
Works at about 20 ml per 15 ml of cordial. It adds alcohol, so keep it out of alcohol-free drinks.
A sealed commercial bottle keeps for months; once open, keep it in the fridge and use it within a few weeks. Homemade cordial keeps a couple of weeks refrigerated. The first sign of turning is a faint fizz rather than a smell.