Seville orange and fennel seed marmalade

Method

1. Squeeze out the juice from all the citrus fruit into the large pan, keeping back all the pips you find. Use a spoon to scrape out any remaining pulp or membrane from the citrus halves and reserve that too.
2. Quarter the juiced citrus shells, then use a sharp knife to slice them into strips of peel. These can either be chunky or fine, depending how you want your marmalade.
3. Put the sliced citrus peel into the pan with the juices, then pour in 2.5 litres water. Firmly tie the retained citrus seeds and any pulp or membrane into the square of muslin/J-cloth and drop it in the pan. Scatter in the fennel seeds, then put the pan over a high heat.
4. Once the fruit mixture comes up to the boil, turn the heat down and cook gently for 1½–2 hours. The peel should be almost translucent and very tender. Lift out the muslin/J-cloth bag and set it aside in a small bowl to cool. Add the sugar to the pan and turn up the heat. Stir regularly to help the sugar dissolve  as it comes to the boil.
5. Meanwhile, squeeze all the syrupy juice from the muslin/J-cloth bag directly into the pan, making sure you get every last drop out. Put two or three saucers in the freezer to chill.
6. Leave the fruit and sugar to boil rapidly for 15 minutes, then test for setting point: remove a tablespoon of marmalade, drop it onto one of the chilled saucers, then pop it into the fridge for a few minutes. If a skin forms that wrinkles up when you push your fingertip through the cooled marmalade, it’s ready. Take the pan off the heat. If the marmalade on the saucer is still very runny, leave it to boil longer, testing every 5 minutes or so until the right texture is reached (some batches can take over half an hour to reach setting point).
7. Meanwhile, prepare the jars. I wash them in hot soapy water, give them a rinse then pop them onto a tray and into a hot oven for 5 minutes or so (see tips).
8. Pour the marmalade into the warm jars (a jam funnel and a ladle makes light work of this job or a jug with a spout can be equally effective). Put the lids on and seal while still hot. Label when cold, then store in a dry, cool, dark place (see tips).