Hull the persimmons and cut into chunks. Place into the bowl of an Instant Pot with the water, lemon juice and sugar. Lock the lid into place, making sure the steam valve is closed, and set to cook on "Manual" on high pressure for 45 minutes.
When the timer beeps, quick release the pressure and open the lid. Puree the cooked persimmons in the pot using an immersion blender.
Add the cinnamon stick to the pot and set the lid on the pot, leaving a small gap allow steam out. Do not lock the lid into place.
Set the slow cooker function to high for 1 hour.
When the timer beeps, add a splash of vanilla and a pinch of salt. Taste and add additional sugar or vanilla as needed. Remove the cinnamon stick before transferring to airtight containers for storing in the refrigerator or freezer.
Notes
For an ultra-smooth butter, peel the persimmons before cooking.
If you do not have an immersion blender, allow the cooked persimmons to cool slightly before carefully transferring to a blender to puree. Add the pureed fruit back to the pot for the next stage of cooking.
If you do not have an Instant Pot, you can follow the same stove-top cooking method as for my Apple Cherry Butter – just note that you will have to babysit it a bit more than you would in the Instant Pot.
Store in an airtight container in the fridge for 1-2 weeks or in the freezer for up to 6 months.