Method
Inspect the elderflower heads and remove any insects that might have found a home in them. Place the heads in a large, clean bowl together with the grated lemon zest and the sliced lemon.
Bring 1.5 litres (52fl oz) of water to the boil in a large pan, remove the pan from the heat and pour the water over the elderflowers. Stir once or twice, cover and leave overnight to infuse.
Strain the infused liquid through a scalded jelly bag or piece of clean muslin into a large jug, then pour the liquid into a large pan (you can use the pan you used for boiling the water). Add the sugar, honey, lemon juice, and citric acid, if using.
Place the pan over a low heat and heat the liquid gently, just enough to dissolve the honey and citric acid, but don’t let it boil.
Use a funnel to pour the hot cordial into sterilized bottles. Seal the bottles with swing-top lids, sterilized screw-tops or corks. The cordial will keep for several weeks in the fridge.
