Step 1

Cut the steak into 1/3-inch thick slices against the grain. Season with salt and pepper to taste.

Step 2

In a large skillet, melt the butter over medium-high heat. Add the beef in batches, searing each side for no more than 20-30 seconds. Remove the steak from the skillet and set aside to rest.

Step 3

In the same skillet, cook the onions until soft. Then, add the garlic and stir until fragrant.

Step 4

Add the mushrooms and sauté until they turn golden.

Step 5

Sprinkle the flour into the skillet and cook for 1 minute, stirring constantly. Then, slowly add the beef broth and continue cooking and stirring until the mixture thickens.

Step 6

Reduce the heat to low, add the Worcestershire sauce, sour cream, and mustard, and stir gently. Cook for 4-5 more minutes until smooth and blended.

Step 7

Return the seared steak to the skillet and cook for 1 minute.

Step 8

Serve the beef stroganoff over egg noodles or rice. Garnish with parsley, and enjoy!