Remove the sealing ring and thoroughly wash the inner pot and the lid with very hot water. Leave the sealing ring off. This is a cultured product so it is important that everything is clean.
Add 1-4 quarts of cream to the inner pot of the Instant Pot. Place the lid on the Instant Pot and lock. The valve can be in either the sealed or unsealed position. Select the "yogurt" setting and change the time to 45 minutes and the temperature to 145 degrees F. This step will result in a thicker sour cream.
After 45 minures at 145 degrees F, remove the inner pot and allow the temperature to drop.
When the temperature of the cream has dropped to 77 degrees F, add the starter culture and wisk it in for a few seconds.
Return the inner pot to the Instant Pot. Place the lid on the Instant Pot and lock. The valve can be in either the sealed or unsealed position. Select the "yogurt" setting and adjust it to "low". It will show a temperature of 90 degrees F. Adjust the time to 16 hours and start.
After 16 hours the sour cream should be fairly thick. Transfer it to a glass container and store it in the refrigerator. It can be stored for 2-3 weeks.