Heat the olive oil or butter in a large, deep skillet over medium-high heat. Add the ground beef, season with the kosher salt and black pepper, and cook until browned, breaking it into small pieces. Drain excess fat if necessary.

Add the diced onion and sliced mushrooms to the browned beef. Cook for 5–7 minutes, stirring occasionally, until the onion softens and the mushrooms release their moisture and begin to brown.

Add the minced garlic and cook for about 30 seconds, stirring constantly so it becomes fragrant without scorching.

Sprinkle the flour over the beef and vegetables. Stir for 1 minute so the flour coats the ingredients and cooks away its raw taste.

Gradually pour in the beef broth while stirring to create a smooth sauce. Add the Worcestershire sauce, Dijon mustard, and paprika if using.

Stir in the egg noodles and bring the mixture to a gentle simmer. Cover and cook for 8–10 minutes, stirring occasionally to prevent sticking, until the noodles are tender.

Remove the skillet from the heat. Stir a little of the hot sauce into the sour cream, then stir that mixture back into the skillet to help prevent curdling.

Taste and adjust the seasoning with additional salt or pepper as needed. Garnish with chopped parsley and serve immediately.