Wash the strawberries very well, trim the ends to discard any leaves and slice in halves. Transfer the sliced strawberries to the instant pot.
Also wash the apples very well, peel, core and roughly slice into medium sized pieces. Transfer the apple slices also to the instant pot.
Add the brown sugar, lemon juice and cinnamon powder, mix everything well.
Close the instant pot with lid in sealing position and cook in high pressure for 10 minutes.
Do a natural pressure release.
Once the pressure is all released, carefully and gradually open the lid.
Add the vanilla extract also to the instant pot, stir the contents and mash the contents using a potato masher.
Simmer the contents using the saute function, while you continue to stir and mash the contents.
Continue to simmer (stir and mash often to avoid burning at the bottom of the pot) for about 20 to 25 minutes until the desired butter consistency is reached (it took 25 minutes for me).
On the final stage of preparation, also add the butter also to the instant pot (if using), stir in and simmer until the butter is melted into the pot and simmer for another one to two more minutes while you stir.
The delicious strawberry apple butter is ready, allow the contents to cool down, once its cooled you can transfer to dry, clean and air tight glass containers and store in refrigerator for about two weeks of time.