Chop the plums roughly, discard the seeds and add the sliced plums to the instant pot.
Add the sugar, lemon juice and water, mix everything well.
Close the instant pot with lid in sealing position and cook for 15 minutes in high pressure. This helps the plums cook really soft and the peels will also get dissolved into the jam as we further prepare the jam.
Do a natural pressure release.
Once the pressure is all released, carefully and slowly open the lid and stir the contents. Also gently mash the contents using a potato masher.
Press the saute button and simmer the contents for about 12 to 15 minutes or until the cooked plums have almost reached a spread consistency. Keep stirring in between to avoid the contents burning at the bottom of the pot, and also mash the contents in between as they are simmering, which will help you to get a smooth consistency. Plum jam will further thicken as it cools down, so make sure to stop the cooking once it reached the spread consistency.
Allow the jam to cool down slightly and transfer to dry, clean glass jars and keep refrigerated for about a week!