Pat the beef short ribs dry with paper towels. Season generously with kosher salt, freshly ground pepper, and ground mustard. Lightly dust the ribs with all-purpose flour.

In a pot, heat canola oil over medium-high heat. Add the seasoned ribs and cook for 4–5 minutes per side until browned. Remove and set aside.

In the same pot, reduce heat to medium and add sliced onion. Sauté for 5–7 minutes until transparent, then add minced garlic and cook for an additional 1–2 minutes.

Pour in beef broth, scraping bottom of pot to deglaze. Bring to a gentle boil before adding the ribs. Cover and simmer for 2.5 to 3 hours until tender.

Remove ribs and strain the cooking liquid to separate it from the solids, creating a smooth sauce base.

Melt unsalted butter in the pot over medium heat. Add mushrooms and sauté for about 5 minutes until softened. Return the strained onions and whisk in flour. Gradually add the cooking liquid and remaining beef broth until thickened.

Reduce heat and stir in heavy whipping cream, sour cream, Worcestershire sauce, and Dijon mustard. Season to taste and simmer for about 5 minutes.

Stir in egg noodles, ensuring they are submerged in the sauce. Cook according to package instructions until tender.

Serve with creamy noodles topped with short ribs and additional sauce. Garnish with parsley or Parmesan cheese.