800g limes (approx, no need to be exact)
1 kilo white sugar
1.2 litres cold water
Equipment: a potato peeler, a very sharp knife, a 30cm square piece of muslin, jam jars and a large saucepan
First of all, place a small plate or saucer into your freezer – you will need this later to test whether the marmalade has set, and it needs to be very cold.
Peel the zest from the limes and the lemon, using a potato peeler (it is easiest to do this from top to bottom, rather than trying to peel around the fruit horizontally). You will get a thin layer of pith attached to the zest, but that’s fine, it will just dissolve.
Using a very sharp knife, shred the zest into very thin strips. If you prefer, you could cut it into larger pieces and put them into a mini food processor – it will taste exactly the same, but the finished marmalade won’t look quite so pretty. Put the shredded zest into your saucepan.
Again, using a sharp knife, slice the white pith away from the fruit, then collect the pith pieces and any pips in the piece of muslin (you could also use a blue J-cloth – I am currently cutting up an old Ikea muslin curtain that used to hang in our office – any thin cotton fabric works, just make sure whatever you are using is clean).
Cut the flesh of the fruit (including the thin pith that holds the segments together) into small chunks and add to the saucepan, along with any juice and the 1.2 litres of water. Try to pick out any pips, though one or two don’t matter. If your family are litigious and likely to give you a dentist’s bill, just don’t share the marmalade with them.
Tie up the muslin from corner to corner and add the muslin pouch to the pan – it is the white pith that contains a lot of the pectin in the fruit, which is what makes the marmalade set.
Cover the pan with a lid, bring to the boil, then turn the heat right down and simmer, covered, for about 1.5 hours.
Remove the muslin pouch from the water and, using a wooden spoon to squash it against the side of the saucepan, squeeze all the liquid from the pouch of pith back into the pan. (You may find it easier to put the pouch into a small sieve and squeeze it in that, holding it over the saucepan). Discard the pith once you’ve squeezed all the liquid out of it – I will leave it up to you whether you rescue the muslin and re-use it (I have a very large curtain to go at and I am supremely lazy, so no prizes for guessing what I do with mine).
Put the saucepan back over a medium heat and add the sugar. Stir continuously until all of the sugar has dissolved completely, making sure to brush down any crystals on the side of the pan. Do not allow the liquid to boil until the sugar has completely dissolved or your marmalade may crystallise. Once the liquid is completely clear, turn up the heat and bring the marmalade to the boil. It may splash, so make sure you use a long spoon for stirring and also ensure that the saucepan has plenty of space, so that the marmalade doesn’t boil all over your stove (been there, it’s not pretty).
Adjust the heat so that the marmalade stays on a fairly rolling boil but isn’t threatening to come up over the top of the pan. Cook for about ten minutes, then test for a set by putting a teaspoon of the marmalade onto your cold plate and then pushing it with your thumb to see if it wrinkles. If the blob of marmalade wrinkles, it is ready, otherwise cook for another two minutes and test again, repeating if necessary. The marmalade does change colour when it is ready, but the difference can be quite subtle, so the cold plate test is the most reliable.
Once the marmalade is ready, pot into hot, sterilised (see note below) jars and seal tightly. The jars must be hot or they will crack when your pour in the hot marmalade.
1. To sterilise your jars, wash in hot soapy water, rinse well, then put on a tray in a 100°C oven for a few minutes until hot. Alternatively, wash the jars in a dishwasher and use them as soon as the cycle has finished, while they are still very hot.
2. In the unlikely event that you discover your marmalade hasn’t set when it has cooled, just tip back into the pan, bring to the boil and then repeat the setting process, checking every two minutes. You will need to wash and re-sterilise the jars.