Set Instant Pot to saute mode. Add the olive oil to the pot and heat. Once hot, add the onion and cook, stirring often, until the onion begins to soften 2-3 minutes. Next, add the minced garlic and cook for an additional 1 minute. Stirring often.
Add the cubed beef to the pot then sprinkle with salt and pepper. Cook, stirring occasionally, until the meat is browned on all sides, about 4-6 minutes. The meat does not need to be cooked all the way through.
Add the worcestershire sauce or coconut aminos to the pot then add ½ cup of beef broth. Stir, scraping down the sides to deglaze the pot so no bits of food are stuck on the bottom of the pot.
In a separate bowl, mix together the tapioca flour with the remaining beef broth until dissolved then add to the pot. Stir in the mushrooms. Close and seal the lid and cook on high pressure (manual) for 10 minutes. It will take about 10 minutes for the instant pot to reach pressure before counting down 10 minutes.
When the time is up, immediately vent the Instant Pot to quick release the pressure, being careful not to burn your hand with the steam. When it’s all released, remove the lid and add the uncooked egg noodles to the pot.
Recover the Instant Pot, seal, and cook on high pressure (manual) for 5 more minutes to cook the noodles. When the time is up, allow the pressure to naturally release for 5 minutes, then immediately vent to release any remaining pressure.
Carefully open the lid and stir. Let the stroganoff cool for a few minutes, then stir in the Greek yogurt or coconut cream. Serve hot, sprinkled with fresh parsley and additional salt and pepper to taste.