Wash the oranges then cut them in half and juice them. Scrape the inside of the halves after juicing and place these onto your piece of muslin (include everything, pith, pips, flesh).
Cut the orange peel halves into half again and then cut the peel into shreds of your desired size, cut these a little bit thinner than you’d like the final result to be as they will puff up slightly.
Gather up your piece of muslin into a pouch and tie it with some kitchen string, Leave one long piece of string so you can tie this to the panhandle.
In your pan you should now have: the juice of the oranges, the cut peel and the pouch of muslin, add 2500g of water put the lid on and leave to soak for 24 hours.
Once the 24 hours are up, bring the mixture to a boil and then turn the heat right down to low and allow to simmer for two hours covered. Give the mixture a little check after an hour and 1.5 hours. If on the second check, the mixture has reduced by around a third and the peel has become soft, you can pop the oven on ready to start warming the sugar as mentioned above. Depending on your hob and how powerful it is will depend on the exact timings here but you are looking for the mixture to have reduced not quite as much as by half and the peel to be a consistency you’d be happy to eat.
Keeping the heat at low, add the sugar, and stir occasionally until the sugar has dissolved completely.
During this next stage try not to stir the mixture at all unless you can see an issue in the pan. Once the sugar has dissolved, increase the heat to medium/high and bring the mixture to a rolling boil. At first, you will have large frothy bubbles, as the mixture finishes this phase the bubbles will decrease to become very small. At this point, you can start checking the temperature with your digital thermometer. The setting point you need to get to is 104.5°C. Once you’re at that temperature, decrease the heat to low and leave for another three minutes then remove the pan from the heat and onto a wire rack.
Leave to cool to 85°C and then start potting into your warm, sterilised jars leaving around 1cm gap at the top.. Once you have filled all of the jars start closing the lids.
Although you will be tempted, you’ll need to leave the marmalade to properly cool and set for a minimum of 48 hours before you can crack open the first jar.
Providing you followed the steps to sterilising the jars correctly, your marmalade should last up to two years!
