01 - Bring a large pot of salted water to a rolling boil. Add egg noodles and cook according to package directions until al dente. Drain thoroughly in a colander and set aside.
02 - In a large skillet over medium-high heat, melt butter. Add chopped onions and sauté for 2-3 minutes until translucent. Add sliced mushrooms and continue cooking 4-5 minutes until mushrooms release moisture and begin to brown.
03 - Stir in minced garlic and cook for 30 seconds until fragrant, stirring constantly to prevent burning.
04 - Add ground beef to the skillet. Cook while breaking up with a wooden spoon until browned completely, about 5-7 minutes. Drain excess fat if needed.
05 - Sprinkle flour over the meat mixture, stirring well to coat evenly. Cook for 1 minute to eliminate raw flour taste.
06 - Gradually pour in beef broth, Worcestershire sauce, and Dijon mustard. Bring to a gentle simmer while scraping browned bits from the skillet bottom. Season with salt and pepper to taste.
07 - Reduce heat to low and simmer for 5-7 minutes until sauce slightly thickens, stirring occasionally.
08 - Remove skillet from heat completely. Gradually stir in sour cream until fully incorporated and sauce becomes smooth and creamy.
09 - Sample the sauce and adjust salt and pepper as needed. If flavor is too intense, add a splash more broth.
10 - Plate cooked noodles and spoon stroganoff generously over top. Sprinkle with fresh parsley if desired. Serve immediately while hot.