My recipe is made over two days and keeps for at least a year. Once the cordial has been poured into bottles, sterilise it in a water bath. Fill the bottles leaving a 2.5cm (1in) gap at the top. Screw the tops, then give them a quarter turn so that the bottles are loosely sealed. Create a false bottom in a pan, tall and wide enough to hold the bottles – a trivet from a pressure cooker, a wooden stand or wads of newspaper. Stand the bottles upright in the pan and pour cold water up to the lower level of the lids. Turn on the heat and and bring the water to 88ºC (190ºF). This will take about 45-60 minutes. Check the temperature using a sugar thermometer. As soon as the temperature is reached, reduce the heat and maintain the temperature for 20 minutes. Using protective gloves, remove the bottles from the pan on to a wooden board. Screw the lids up tightly and leave to go cold. Once opened, store the cordial in the fridge.

Elderflower Cordial

Makes 1.75 litres ( 3pints)

15 large elderflower heads, stalks and leaves removed
1kg granulated sugar
2 lemons, washed and sliced
2 oranges, washed and sliced
2 limes, washed and sliced
30g citric acid
1 litre boiling water

1. Dissolve the sugar in the water in a large bowl. Add the remaining ingredients. Cover with a clean cloth and leave for 48 hours, stirring occasionally.

2. Strain the cordial through a jelly bag made from muslin and pour it into bottles with screw top caps. Seal the bottles loosely and sterilise them in a water bath 88ºC (190ºF) for 20 minutes. Carefully remove the bottles from the pan and place them on a wooden board. Seal the bottles and leave to cool.

To serve, dilute 1 part cordial to 5 parts water. I bottle my cordial in 300ml bottles from the Bristol Bottle Company.