20-30 freshly picked heads of elderflower
Zest of 2 lemons and 1 orange
Up to 1.5 kg granulated sugar
Up to 200ml freshly squeezed lemon juice (3-5 lemons, depending on size)
Tartaric acid (optional)
Shake any insects of the elderflowers, then place them in a large bowl with the lemon and orange zest and pour over enough water just boiled water to cover the flowers completely (1 ½ -2 ). Cover and leave for at least 4 hours, or overnight, until cold.
Strain the liquid through muslin, a clean cotton cloth or a jelly bag, gently squeezing it to extract all the juice. Measure the amount of liquid and pour it into a saucepan. To every 500ml liquid, add 350g sugar, 50ml lemon juice and a heaped teaspoon tartaric acid if you are using it. Heat gently to dissolve the sugar, stirring occasionally. Bring to a gentle simmer and skim off any skum. Let the cordial cool, then strain once again through muslin.
Pour the cordial through a funnel into clean bottles, filling them to within about 2-3 cm of the top. Seal the bottles with screw tops or corks.
To serve, dilute to taste with ice-cold water at least 5-1 water to cordial.