Peel and core the pears. Chop them into small pieces.
Place pear, apple- and lemon juice into the Instant Pot.
Select Manual mode and cook at high pressure for 8 minutes. When the time is over, turn it off and let the pressure release on its own, this will take about 8-10 minutes. Carefully turn the vent to “Venting,” just to release any extra pressure that might still be in there. Remove the lid.
Use a blender or a food processor to blend pear mixture until smooth.
Add sugar, ascorbic acid, spices and pear mixture into the Instant Pot.
Select Sauté and adjust to NORMAL. Simmer the pear butter for 30-40 minutes, or until thickened to desired consistency. Press Cancel.
Remove star anis and cardamon pods.
Pour into hot, sterilized jars and seal, allowing for 1/4-inch head space between the pear butter and the rims of the jars.