Heat olive oil in a large stockpot or Dutch oven over medium high heat. Add ground beef and cook until beef has browned, about 3-5 minutes, making sure to crumble the beef as it cooks; season with salt and pepper, to taste. Drain excess fat.
Stir in mushrooms and cook, stirring occasionally, until tender and browned, about 3-4 minutes. Stir in tomato paste until lightly browned, about 1 minute. Stir in flour until lightly browned, about 1 minute.
Stir in beef broth and egg noodles. Bring to a boil; cover, reduce heat and simmer until noodles are cooked through, about 10-12 minutes.
Stir in sour cream and Dijon mustard until well combined.