Sterilise three 400g jars (see tip, below) and put a saucer in the freezer to chill (you will use this later to test whether the jam has set).

Cut each peach half into six to eight pieces, then tip the fruit into a large saucepan set over a medium- low heat along with the lemon zest and juice. Bring the mixture to a gentle simmer and bubble for 10 mins –the peaches will turn juicy and start to soften.

Crush the cardamom seeds with a pestle and mortar and add these to the peach mixture along with the sugar. Reduce the heat to low and stir until the sugar has dissolved. Once dissolved, turn up the heat to medium-high and bubble for 15-20 mins, stirring occasionally to prevent the jam from catching, until the jam is set and has reached 105C on a sugar thermometer. If you don’t have a thermometer, spoon a little of the jam onto the chilled saucer, leave it for 30 seconds, then draw a line through it with your finger – if it wrinkles and doesn’t flood the gap, it’s ready. If not, boil for 2 mins more, then check again.

Leave to cool for 10-15 mins to allow a more even distribution of peach chunks. You may find that a little foam rises to the top; if so, simply stir this back into the jam. Use a funnel to help you fill the jars or do this with a ladle, being very careful as the jam will still be extremely hot. Seal with the lids, then store in a cool, dark place. Unopened jars will keep for up to a year. Once opened, keep the jam in the fridge and eat within a month.