Elderflower cordial

Method

1. Put the sugar in an enamel, glass or ceramic bowl with 1.75 litres boiling water. Stir to dissolve the sugar, cover with a clean tea towel and leave to cool completely.
2. Zest and slice the lemons and thinly slice the limes. Add the zest and fruit slices to the cold sugar solution. Shake the flowers to displace any hidden insects, and remove the stalks. Add the flowers to the bowl with the citric acid, then stir. Cover with cling film and leave for 36 hours in a cool dark place.
3. Strain through a fine sieve, then strain again, this time through a sieve lined with a fine muslin cloth. Decant into sterilised glass bottles and keep in a cool dark place for up to 2 months. Once opened, refrigerate and use within a month.