01 -
Prepare the ingredients by thinly slicing beef sirloin, chopping the onion, and mincing the garlic.
02 -
Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the sliced beef, season with salt and black pepper, and sauté until browned, approximately 3 to 5 minutes. Remove the beef from the skillet and reserve.
03 -
Add the remaining tablespoon of olive oil to the same skillet. Sauté the chopped onion and minced garlic for 2 minutes. Introduce the sliced mushrooms and cook until softened, around 4 to 5 minutes.
04 -
Evenly sprinkle the flour over the sautéed vegetables and stir well, cooking for an additional 1 to 2 minutes.
05 -
Gradually pour in the beef broth while stirring continuously to prevent lumps, then bring to a gentle simmer.
06 -
Stir in the Worcestershire sauce, Dijon mustard, and sour cream. Cook until the sauce is fully incorporated and thickened slightly, about 5 minutes.
07 -
Return the reserved beef to the pan, mixing thoroughly. Simmer for 2 to 3 minutes until the meat is heated through.
08 -
Taste the sauce and adjust seasoning with additional salt and pepper as required.
09 -
Remove the skillet from the heat. Garnish with freshly chopped parsley and serve immediately over cooked egg noodles or rice.