Bring a large pot of salted water to a boil, add egg noodles and cook for 8-10 minutes until al dente, then drain and set aside.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat, add beef slices and sear for 3-4 minutes until browned, then remove beef and set aside.

In the same skillet, add remaining olive oil, then add diced onion and sliced mushrooms and sauté for 5-7 minutes until softened and golden brown.

Add minced garlic to the skillet and cook for 1 minute, stirring constantly to prevent burning.

Sprinkle flour over the vegetables, stir to combine, and cook for 1-2 minutes to remove the raw flour taste.

Gradually pour in beef broth while stirring to avoid lumps, bring to a simmer and cook for 2-3 minutes until the sauce begins to thicken.

Return the seared beef and any accumulated juices to the skillet, reduce heat to medium-low and simmer for 5 minutes to meld the flavors.

Remove the skillet from heat and stir in sour cream and Dijon mustard until the sauce is smooth and creamy.