Elderflower cordial cocktail

For the elderflower cordial: gently rinse the elderflowers then put them in a large bowl. Grate the lemon zest over the flowers then slice the lemons and add them to the bowl.

Put the caster sugar and water in a saucepan and bring to the boil, stirring to make sure the sugar dissolves. Once it has come to the boil take off the heat and allow to cool.

Pour the sugar syrup over the elderflowers and stir in the citric acid (if using). Cover with a cloth and leave to infuse in the fridge for 24 hours.

Strain the cordial through a muslin cloth and into glass bottles.

For the cocktail: pour 60ml of white rum and 60ml of elderflower cordial into a glass. Add a couple of ice cubes, a sprig of mint and top up with cold water.