The first step is to turn on your Instant Pot to the "Saute" function. Put in the oil and allow to heat up for about 1 minute.
Add in your onion and salt. Stir this around for about 4 minutes, until the onion softens a bit.
Grab a teaspoon of salt and pepper and season the beef. Add the beef to the Instant Pot. Brown the beef on all sides, which should take around 2 minutes.
Add in your thyme and garlic, and then cook for about 30 seconds. Put the soy sauce in next, and then add in your mushrooms.
Stir this all together and then add in your flour until it is all evenly mixed. Put the chicken broth and 1/2 teaspoon salt into this.
Close the lid on the Instant Pot and seal the valve. Cook on "Manual" high pressure for 10 minutes.
Use the quick release option on the pressure once the timer is done.
Add in your egg noodles. Close the lid and seal the valve. Cook on "Manual" high pressure for 5 minutes.
Allow for a natural release of pressure for 5 minutes, then quick release remaining pressure.
Open the lid and then stir in the sour cream and serve.