1cupplain whole milk Greek yogurtdo not use nonfat or it will curdle
Chopped fresh parsley or thymeoptional for serving
Set Instant Pot to SAUTE. Add the oil and butter. Once hot, add the onion and 1/2 teaspoon salt. Cook, stirring often, until the onion begins to soften but does not brown, 3 to 4 minutes.
Sprinkle the beef with remaining 1 teaspoon salt and pepper. (You can toss the beef cubes together with salt pepper in a bowl, or to save a dish I like to do this right on the cutting board.) Add to the pot. Cook, stirring occasionally, until the meat is browned on all sides, about 4 to 6 minutes. Add the dillweed, garlic powder, onion powder, Worcestershire sauce, and mustard. Pour in 1/2 cup of the beef broth. Stir, scraping a wooden spoon or spatula along the bottom of the pot, to ensure you remove any stuck-on bits of food (this will avoid a “burn” warning).
Stir in the mushrooms, then sprinkle the flour over the top. Stir until evenly incorporated. Pour in the remaining beef broth. Close and seal the lid. Cook on HIGH pressure (Manual) for 10 minutes. When the time is up, immediately vent the Instant Pot to quick release the pressure.
Once you can safely open the pressure cooker, carefully open the lid and add the egg noodles. Recover the Instant Pot, seal, and cook on HIGH (manual) for 5 minutes. 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. Serve hot, sprinkled with fresh parsley and/or thyme
TO STORE: Store leftovers in the refrigerator for up to 3 days.
TO REHEAT: Reheat gently in the microwave or on the stovetop with a splash of water, milk, or broth to keep them from drying out.
TO FREEZE: Freeze stroganoff in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating.