Lemon and Lime Marmalade

Begin by measuring 3 pints (1.75 litres) of water into a preserving pan, then cut the lemons and limes in half and squeeze the juice out of them.

Add the juice to the water, and place the pips and any bits of pith that cling to the squeezer on the square of muslin (laid over a dish or cereal bowl first). Now cut the lemon and lime peel into quarters with a sharp knife, and then cut each quarter into thinnish shreds. As you cut, add the shreds to the water and any pips or spare pith you come across should go on to the muslin.

The pith contains a lot of pectin so don't discard any, and don't worry about any pith and skin that clings to the shreds – it all gets dissolved in the boiling. Now tie up the pips, etc loosely in the muslin to form a little bag, and tie this on to the handle of the pan so that the bag is suspended in the water. Then bring the liquid up to simmering point and simmer gently, uncovered, for 2 hours or thereabouts until the peel is completely soft – test a piece carefully by pressing it between your finger and thumb.

Towards the end of the simmering time pre-heat the oven to gas mark 3, 325°F (170°C). Pour the sugar into a roasting tin, lined with foil, and place it in the oven to warm gently for 10 minutes. At this point pop the saucers into the freezing compartment of the fridge.

Next remove the bag of pips and leave it to cool on a saucer. Then pour the sugar into the pan and stir it now and then over a low heat until all the crystals have dissolved (check this carefully, it's important). Now increase the heat to very high, and squeeze the bag of pips over the pan to extract all of the sticky, jelly-like substance that contains the pectin. As you squeeze you'll see it ooze out. You can do this by placing the bag between two saucers or using your hands. Then stir or whisk it into the rest.

As soon as the mixture reaches a really fast boil, start timing. Then after 15 minutes take the pan off the heat and spoon a little of the marmalade on to one of the cold saucers from the fridge and let it cool back in the fridge. You can tell – when it has cooled – if you have a 'set' by pushing the mixture with your little finger: if it has a really crinkly skin, it is set. If not, continue to boil the marmalade and give it the same test at about 10-minute intervals until it does set.

After that remove the pan from the heat (if there's a lot of scum, most of it can be dispersed by stirring in half a teaspoon of butter, and the rest can be spooned off). Leave the marmalade to settle for 20 minutes before potting into jars that have been washed thoroughly in warm soapy water, rinsed, dried, then warmed in a medium oven for 5 minutes. Label when completely cold.