Let steak come to room temperature. Season with salt & pepper on both sides. Heat 2 tbsp of oil or butter on a large skillet, medium heat.
While waiting, prepare your mushrooms, onion, and garlic.
Cook steak for 3 mins on one side, flip over, and cook for another 3 mins. Remove from skillet & set aside on a plate.
Add onions into the same skillet and stir. After a few minutes, add in mushrooms until they are browned and the onions are soft (2-3 minutes). Add in garlic. Turn heat to low. Let the veggies soak in all those steak juices for a minute or two.
Mix together broth, Worcestershire sauce, & flour in a small bowl. Add into skillet and stir. Simmer for 5-6 minutes.
While the sauce simmers, cut the steak into slices and roughly chop some fresh parsley if you please.
Add in sour cream (traditional) or Greek yogurt (healthier) to the skillet. Add the meat and optional parsley back into the dish. Season with garlic powder and black pepper.
Serve over egg noodles (traditional) or rice, quinoa, cauli rice, etc.