Place the stainless steel pot in the Instant Pot. Press the “Saute” button until it’s on “More.” Add the butter.
When the butter is melted, add the onion and cook for about a minute, then add the mushrooms and saute for 3 more minutes. Finally, add the garlic and cook for another minute, stirring occasionally.
Add the farro and broth and stir, scraping up anything that has stuck to the bottom of the pot. Then lock the lid in place. Close the pressure release valve and press the “Pressure Cook” button until it’s on “Normal” and press the “Pressure Level” button until on “High” (High is the default). Press the +/- buttons until it says 00:10 for 10 minutes.
When done, let the Instant Pot naturally release for 10 minutes (just do nothing and it will start counting up). Then press the “Cancel” button to turn off the Instant Pot and quick release the remaining pressure by opening the pressure valve, steering clear of the steam.
After the pressure is released and the float valve falls, remove the lid. It will still look a bit soupy. Turn the Instant Pot back on “Saute” and leave to simmer uncovered for about 3 minutes, stirring frequently. Then add the Asiago cheese, thyme, and salt and mix in well.
Turn off the Instant Pot and serve.