Suntinas are available from mid-December to the end of February and have a charming tangerine flavour which makes a delightfully different marmalade, and I think the nice thing about having a choice of marmalades is you never get bored.
This recipe is from Delia's Winter Collection. Makes 2 x 1 litre or 4 x 0.5 litre jars
Begin by measuring the water into a preserving pan, scrub the oranges and lemons then cut them all in half and squeeze the juice out of them.
Add the juice to the water, then 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). Now cut the 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 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 and pith loosely in the muslin to form a little bag, and tie this onto the handle of the pan so that the bag is suspended in the water. Then bring the liquid up to simmering point and gently simmer, uncovered, for 2 hours or thereabouts until the peel is completely soft – test a piece by squashing it against the side of the pan. At this point pop the plates into the freezing compartment of the fridge.
Next remove the bag of pips and leave it to cool on a saucer. Then warm the sugar, pour it 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 (you'll see the pectin 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 remove the pan from the heat, spoon a little of the marmalade on one of the cold plates from the fridge and let it cool back in the fridge. When it has cooled you can tell 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. (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.
Finally pour the marmalade, using a funnel or a ladle, into the jars that have been washed thoroughly in warm soapy water, rinsed and dried, then warmed in a medium oven for 5 minutes. Cover with waxed discs and seal while still hot. Label the jars when quite cold.