Cook the beef:
Spray a large skillet with olive oil spray. Cook ground beef or sliced sirloin over medium-high heat until browned. Drain excess fat, if any. Set aside.
Sauté veggies:
In the same pan, sauté onion and garlic for 2–3 minutes. Add mushrooms and cook until softened and browned (about 5–7 minutes).
Deglaze and flavor:
Add Worcestershire sauce, Dijon mustard, paprika, and beef broth. Bring to a simmer. Return the beef to the skillet and let everything simmer together for 5–7 minutes.
Make it creamy:
Remove from heat and let cool slightly before stirring in the Greek yogurt and sour cream (this prevents curdling). Mix until smooth.
Serve:
Spoon over cooked egg noodles or preferred pasta substitute. Garnish with parsley if desired.