Makes about 3x 450g jars
Remove the sliced oranges and lemons from the discarded elderflowers. Don't worry if any odd elderflowers are attached to the slices, that is part of this marmalade's charm. Finely shred the slices including the rind, ensuring you remove all the pips as this can make the marmalade unpleasantly bitter.
Once shredded, weigh the chopped mass. Write this weight down then and add the same weight of water to a heavy bottomed pan and bring to the boil. Simmer very gently with the lid off until the rind is soft enough to squash between your fingers. My marmalade recipe says 2 hours but it is for Seville marmalade the rinds of which are apparently tougher than most citrus fruit. I think it took about 30-60 minutes to be soft enough.
When you think the rind is soft enough add double the weight of the shredded fruit in sugar. Stir to dissolve and bring to a rolling boil and keep it boiling for 10 minutes. Test for set on a saucer that has been placed in the freezer. The marmalade is set when about a teaspoon of marmalade wrinkles when cooled as you push the edge of it towards the middle. Turn off the heat once the marmalade has reached setting point and leave for about 10 minutes before pouring into sterlised jars (see below). The reason for leaving it to cool a little is to stop start the jam setting and stop all the rind floating to top.
How to sterilise jars:- Soak the labels off in warm soapy water and clean thoroughly inside and out. Drain then place into cold oven. Heat the oven and jars to 150C. The jars are sterilised once the oven reaches temperature. I sterilise lids (both old and new) by simmering them in boiling water whilst the jars are sterilising in the oven.