Pour the milk into the instant pot stainless steel pan. Seal the lid and press the “Yogurt” button until it says “boil”. When it beeps, remove the lid (no pressure release is needed since there was no pressure built up). Stir and insert a thermometer. The goal is to get the milk just over 180 degrees F. If it’s not to temperature yet, then click on the “Saute” button and stir occasionally until the milk is over 180 degrees F.
Using oven mitts carefully remove the stainless steel pan from the Instant Pot and set on a heat resistant surface. Let it sit out for about an hour, checking the temperature occasionally, you want it to get to 110 degrees F.
Once the milk is below 110 degrees F, use a ladle or spoon to move about 1 cup of liquid to a bowl. Add the two tablespoons of yogurt to the bowl and mix well with a fork. Pour the yogurt/milk mixture back into the pan with the milk, mix together with a spoon, and put the stainless steel pan back in the Instant Pot. Seal the lid. Since this is not a pressure setting, it doesn’t matter if you’ve closed the pressure valve or not.
Press the “Yogurt” button until it’s on the “Normal” setting and press the +/- buttons until it says 10:00 for 10 hours. For a less tart yogurt, you could change it to 8 or 9 hours.
When the Instant Pot is done, stir the yogurt. If you just want regular yogurt, then move to the next step. If you want Greek yogurt, then set a large colander over a large bowl or over your sink and line it with a cheesecloth. Pour the yogurt into the colander and let it sit for an hour or two to strain out the whey. If you’re using a large bowl, you may need to occasionally pour out the whey and then continue to strain. You can save the whey to use for other purposes, or just pour it down the sink.
Move the finished yogurt to a storage container, add any flavorings or sweeteners, and refrigerate.