Heat 1 tablespoon of butter in a Dutch oven over high heat. Season the beef strips generously with salt and pepper. Add the beef to the skillet in a single layer (cook in two batches if necessary so the meat sears rather than boils). Sear for 1 to 2 minutes per side until deeply browned. Remove the beef and its resting juices to a plate.
yum!Method
Lower the heat to medium-high. Add 1 more tablespoon of butter to the skillet. Add the diced onions and sliced mushrooms. Sauté for 5 to 7 minutes until the mushrooms release their moisture, the water evaporates, and everything turns golden brown. Stir in the minced garlic and cook for 1 more minute until fragrant.
Push the vegetables to the side of the pan. Add the remaining 2 tablespoons of butter to the center and let it melt. Sprinkle the flour over the butter and vegetables, stirring constantly for 1 minute to cook out the raw flour taste. Add the tomato paste and cook for 30 seconds to caramelize it slightly.
Gradually whisk in the beef broth, scraping up all the savory browned bits from the bottom of the pan. Stir in the Dijon mustard and Worcestershire sauce. Bring the mixture to a gentle simmer, reduce the heat to low, and let it thicken for 3 to 4 minutes.
Remove the dutch oven from the heat entirely. (Adding cream to a boiling pan will cause it to curdle). Stir in the cream until the sauce becomes a smooth, velvety brown color.
Fold the seared beef strips and their resting juices back into the creamy mushroom sauce. Taste for salt and pepper. Serve immediately over the warm egg noodles, or some jasmine rice, garnish with a sprinkle of fresh parsley.
