Pour the milk into the Instant Pot’s insert. Lock on the lid. It does not matter if the steam vent is open or closed. Press the 'Yogurt' button, then press 'Adjust' so the digital readout says 'Boil' or 'HIGH.'

After this, on some Instant Pot models, you'll need to press the 'start' button. Eventually it will bring the milk to 180° F (this kills off undesirable microorganisms). It usually takes about 30 minutes.

When it's done, the Instant Pot will beep and its readout will say 'Yogt.'

Right after the Instant Pot beeps, turn it off and lift out the insert of hot milk. Put the thermometer in the milk and wait until it’s 116° F. This can take as long as an hour.

To speed down the cooling, set the insert of hot milk in a bath of ice water and stir the milk; the temperature will drop in about 5 minutes.

Remove the thermometer. There will be a film of coagulated milk on the surface of the milk; carefully lift this off with a spoon and discard.

Put the starter in a medium bowl and add about ½ cup of the warm milk. Whisk until smooth, then pour into the insert of milk and whisk to combine.

Set the insert of milk back in the Instant Pot, lock on the lid, and press YOGURT. On some models, you'll need to press 'adjust' and change the setting from 'HIGH' to 'MEDIUM.'

The Instant Pot will incubate your yogurt for 8 hours before switching itself off.

Start checking on your yogurt after 4 hours. The yogurt is set when it jiggles all as one unit if you carefully nudge the insert.

Once your yogurt is set, gently lift the insert from the cooker. Let it cool to room temperature (about 2 hours), then set it in the refrigerator.

The yogurt might seem lumpy after it's been chilled, but a vigorous whisking will smooth it out. At this point, you may strain it or transfer it to sterile containers.