Turn leftover prime rib into a rich, creamy soup with mushrooms and simple ingredients. This easy prime rib soup recipe is perfect for cozy, low-effort meals.
In a large dutch oven on medium heat, sauté diced onions in the butter until they become translucent. Add the garlic and dried thyme leaves, cooking just until they become fragrant.
Add the beef broth to the dutch oven along with the beef broth base, Worcestershire sauce, and dijon mustard. Bring the broth mixture to a simmer. Taste for salt at this point, adding some along with fresh ground pepper if desired.
Add the sliced mushrooms to the simmering broth and cook until the mushrooms are softened.
In a separate mixing bowl, whisk the sour cream along with some of the beef broth. This will help loosen the sour cream so that it mixes easier into the soup.
Pour the sour cream mixture into the soup, stirring until it's combined. Again, taste the broth. Make sure your salt level is good. If you need more, add more.
Add in the prime rib pieces, cooking until they're just warmed through.
Garnish with a dollop of sour cream, fresh herbs, and fresh cracked pepper. We always have to serve with a side of crusty bread for dunking. Enjoy!