Use a clean quart-sized mason jar and fill it about 90% with your chosen milk (you can use any fat percentage; we prefer 1%).

Place the mason jar on the rack that comes with your Instant Pot. Do not put a cover on the jar.

Warm the milk

Put about 1 cup of water in the bottom of the Instant Pot. Close the top and set to the sealing position.

Select the STEAM setting and set the time for 2 minutes.

When the pressure has been reached and the 2 minutes are up, let the steam release naturally. At this point, you'll be tempted to rush things and let the steam out manually, but trust me, it is best to wait 10 minutes or so for the float valve to drop. It allows the container to cool down naturally, which you'll need for the next step anyway.

Remove the jar of milk from the Instant Pot using a canning jar lifter and place it onto a wire rack.  If it's cold outside, consider placing the jar on your cool porch or front step to help the cooling process.  Do NOT be tempted to place the jar in cold water (or snow) as you might if you were making yogurt in metal (it will crack).

You need to wait for the yogurt to get down to 108-111 degrees (my Instant Pot directions say 115, but I find it works better to let it cool down just a bit more).  This will probably take 30-45 minutes, depending on how cool your environment is.  Set your timer for 15-minute intervals and check the yogurt with a meat or candy thermometer.  Alternatively, you can go with your gut and wait for it to reach "warm body temperature."  Get some other stuff done while it cools!

Cool it down

Once your milk is down to about 108 degrees, pour a small portion into another container.  Into this milk, add either 2 Tablespoons of yogurt you've made previously (we also find that a nice thick Greek Yogurt does the trick) OR one package of yogurt starter.  Mix this thoroughly into your "sample" then gently stir the separated milk into the jar.  Mixing it separately lets you get it better integrated and temperature adjusted without disturbing the whole quart of milk.

Stir in your starter

Now, place your quart container back into the Instant Pot on the rack (still uncovered). Add another cup of water. Cover the Instant Pot and select the Yogurt program for the maximum amount of time (about 7.5 hours or overnight).

After the yogurt cycle, take the yogurt out of the Instant Pot, and put it in the fridge to set.  You'll be able to enjoy it about 4 hours later!