Wash the blueberries and add them to the instant pot.
Add the sugar, mix well with the berries.
Also add the lemon juice and water, stir well.
Close the instant pot with lid in sealing position and press manual or pressure cook and cook in high pressure for 2 minutes.
Once the cooking is done, press the 'keep warm/cancel' button and wait for a natural pressure release.
Once the pressure is all naturally released, carefully open the lid by turning to the venting position.
Add the vanilla extract also to the instant pot, stir well and begin to simmer the contents.
Meanwhile take a little liquid from the pot and add to the cornstarch to make a mixture. Make sure there are no lumps in the cornstarch mixture.
Add this cornstarch mixture to the instant pot, stir well and continue to simmer the contents for another (make sure to keep stirring at this point) for another 5 to 6 minutes until the jam is almost thickened to the jam consistency. Keep in mind that the jam will thicken a little more as it cools down so do not overcook the contents.
Once the jam is cooled enough (while still warm), transfer to dry, clean glass jars and store refrigerated for up to one week.