Cut the yuzu in half. Squeeze its juice and remove the seeds. Do not throw out the seeds and juice because they will be used later.
When the cutting and squeezing is done, remove any fiber from the yuzu citrus and chop. You could also use a slicer or a vegetable peeler.
Put the chopped yuzu into a pot. Add plenty of water (not listed) to soak the yuzu and heat until it boils. When boiling, turn the heat to low and simmer for 5 minutes (to remove bitterness).
Put the seeds from Step 1 and 200 ml of water (not listed) into a pot. Bring it to a boil over high heat to remove the pectin in the seeds. Pass it through a colander or a sieve and remove the seeds.
Put the juice (Step 1), peel (Step 3), and water with the seeds removed (Step 4) into a pressure cooker and turn it on.
After it comes to a boil, cook for 2 minutes under pressure and over medium heat. Turn the heat off and set it aside until the pin drops.
When it's done, uncover the lid and add sugar and a little salt. Heat until your preferred thickness. Transfer in a sterilized bottle and voila!
Story Behind this Recipe
I received lots of yuzu citrus as a gift.
If you're concerned about the bitterness, repeat Step 3 2-3 times. When heating the jam in Step 7, it's all right if it's slightly runny - it will thicken when it's cooled.