Cook the noodles: In a large stockpot, boil generously-salted water and cook the egg noodles until al dente, following the package directions. Once done, drain the noodles. For optimal timing, start cooking the noodles when you begin Step 4.

Sauté the steak: While waiting for the pasta water to boil, melt 2 tablespoons of butter in a large sauté pan over medium-high heat. Arrange the steak in a single layer, seasoning with ample pinches of salt and pepper. Let the steak sear undisturbed for about 3 minutes. Flip and cook the other side until browned, approximately 2-3 more minutes. Remove the steak from the pan with a slotted spoon, place it on a clean plate, and set aside. If necessary, cook the steak in batches using 1 tablespoon of butter per batch.

Sauté the veggies: Add the remaining 2 tablespoons of butter to the pan. Once melted, add the sliced onions and sauté for about 3 minutes. Add the mushrooms, stirring occasionally, and cook for an additional 5-7 minutes until the mushrooms are tender and the onions are soft. Add the garlic and sauté for another minute, stirring occasionally. Pour in the white wine and deglaze the pan, scraping up the browned bits from the bottom with your spoon. Let the mixture cook down for another 3 minutes.

Finish the sauce: While the wine is reducing, whisk together the beef stock, Worcestershire sauce, and flour in a separate bowl until smooth. Pour this mixture into the sauté pan, stir well, and let it simmer for 5 minutes, stirring occasionally. Incorporate the Greek yogurt (or sour cream) and the cooked steak, stirring until everything is well combined. Taste and adjust seasoning with additional salt and pepper if needed.

Serve: Serve the stroganoff warm over the cooked egg noodles, garnished with a sprinkle of fresh parsley and an extra twist of black pepper, if desired.