Juice the fruit, and pass the juice through a sieve to remove the seeds. Put the seeds and membrane from step 3 in a paper pack (or wrap in cheesecloth or cotton gauze).
Take the citrus pulp out with a spoon to separate it from the peel. There is still some seeds and juice left in the membranes, so let it drip down into a bowl.
Finely shred the peel, put into a large bowl of water and wash gently by squeezing with your hands, changing the water several times. Leave to soak overnight in plenty of water.
Drain off the water from step 4. If the water is no longer yellow, the bitterness should be gone. Put the wrapped seeds and membrances in a pot with the shredded peel, and add enough water to cover. Simmer for about 1 hour.
When the peel is tender, add the juice and sugar. If you add sugar from the beginning the peel will nto become tender, so add it in 2 to 3 batches.
Add all the sugar and simmer for a while. When it is syrupy, it's done. It should take about an hour. It will thicken when cooled, so stop simmering when it's still a bit liquidy.
Story Behind this Recipe
Enjoy the vitamin C of yuzu! You can take in the whole healthy goodness of yuzu in this marmalade. I was shocked to learn that most of the yuzu jam sold in stores is imported.
Change the water several times in step 4. In step 5, just add enough waer to cover, since more moisture will come out of the fruit as it cooks. The seeds have lots of pectin which will gel the marmalade, so simmer it with the fruit. Yuzu peel is tough, and it will become softer if you simmer it without sugar at first.