It’s inevitable: when you make a large pot roast, you’ll have leftovers. Rather than reheating the same meal for days, transform that remaining beef into something fresh and satisfying.
If you’re tired of the usual leftover routines—sandwiches, casseroles, or reheated slices—try a flavorful soup that highlights the beef instead of hiding it. Leftover pot roast is an excellent base for a rich, comforting pot roast mushroom soup that’s quick to make and full of savory depth.
This recipe works just as well with leftover prime rib or other roasted beef: simply chop or shred the meat and add it toward the end of cooking. The base of sautéed onions, garlic, and thyme builds an aromatic foundation, while browned mushrooms contribute earthy umami.
After the mushrooms and aromatics are nicely caramelized, deglaze the pan with balsamic vinegar and beef stock to lift the browned bits and enrich the broth. A cornstarch slurry thickens the soup slightly, creating a velvety texture that clings to tender chunks of beef.
As the soup simmers, the aromas will fill your kitchen and make it hard to resist sneaking a taste. This pot roast mushroom soup is the kind of recipe that will likely eliminate your leftover pile in one sitting.
Below is the recipe card for Pot Roast Mushroom Soup. It serves about four and takes roughly 45 minutes total time to prepare and cook. Keep reading for ingredient amounts, step-by-step instructions, and notes on achieving the texture you prefer.
Pot Roast Mushroom Soup
No reviews
- Author: Nikki Cervone
- Total Time: 45 minutes
- Yield: 4 servings
Description
Not sure what to do with leftover pot roast? Turn it into a hearty mushroom soup with a rich, savory broth. This recipe highlights browned mushrooms, aromatic onions, garlic, and thyme for comforting, flavorful results.
Ingredients
- 2 tablespoons olive oil
- 1 small onion, diced (about 1 cup)
- 2 cloves garlic, minced
- 1 teaspoon chopped fresh thyme, plus more for garnish
- 8 ounces button mushrooms, stems removed and sliced
- 2 tablespoons balsamic vinegar
- 4 cups beef stock or beef broth, divided
- 2 tablespoons cornstarch
- 2 cups chopped or shredded cooked pot roast
- 1/2 teaspoon salt, plus more to taste
- 1/4 teaspoon black pepper, plus more to taste
Instructions
- Heat the olive oil in a large pot over medium heat. Add the onion and sauté about 5 minutes, until soft and translucent.
- Add the garlic and thyme and sauté an additional 30 seconds, stirring constantly to prevent browning.
- Add the mushrooms and cook, stirring occasionally, until they are dark brown and have released their moisture, about 5–8 minutes.
- Stir in the balsamic vinegar and 3 1/2 cups beef stock, scraping up any browned bits from the bottom of the pot. Bring to a boil over high heat, then reduce to medium and simmer 5 minutes.
- Whisk the remaining 1/2 cup beef stock and cornstarch in a small bowl until smooth. Slowly pour the slurry into the soup, whisking constantly to incorporate. Simmer another 5 minutes to thicken.
- Add the chopped or shredded pot roast. Cook 10–20 minutes, stirring occasionally, until the soup reduces and thickens to your preference.
- Season with salt and pepper to taste. Serve in bowls and garnish with chopped thyme.
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Category: Beef
- Method: Stovetop
- Cuisine: Soup
Cooking by the Numbers…
Step 1 – Prep
Measure the olive oil, balsamic vinegar, beef stock, and cornstarch. Set out salt and pepper. Dice the onion, mince the garlic, chop the thyme, remove mushroom stems and slice, and shred or chop the pot roast. Larger pieces keep the soup hearty; shred more finely if you prefer.
Step 2 – Sweat the Aromatics
Heat the oil in a large pot over medium. Add the onion and sauté until soft and translucent, about 5 minutes. Add garlic and thyme and cook 30 seconds more, stirring constantly to avoid browning.
Step 3 – Cook the Mushrooms
Add the mushrooms and cook until deeply browned and their moisture has evaporated, about 5–8 minutes.
Step 4 – Deglaze the Pan
Add balsamic vinegar and 3 1/2 cups beef stock, scraping up browned bits. Bring to a boil, reduce to medium, and simmer 5 minutes. If you find balsamic too tangy, omit it; no substitution is necessary.
Step 5 – Thicken
Whisk the remaining 1/2 cup stock with cornstarch until smooth. Slowly whisk the slurry into the simmering soup, then simmer 5 minutes more to thicken.
Step 6 – Add the Meat and Reduce
Stir in the pot roast and cook 10–20 minutes, depending on how much you want the broth reduced and concentrated. Season with salt and pepper, transfer to bowls, and garnish with thyme.
Exactly How Much Should I Reduce the Liquid?
Reduce the broth to the consistency you prefer. For a thinner, slurpable soup, simmer no more than about 15 minutes after adding the meat. For a thicker, stew-like texture, simmer closer to 20 minutes or longer; note that longer reduction will reduce the final yield.
This soup is wonderful with a hunk of crusty bread for dipping. If you need a gluten-free option, serve it with gluten-free bread, roasted potatoes, or creamy polenta.
Pair this pot roast mushroom soup with other comforting sides for a nourishing meal the whole family will enjoy.
Photos by Nikki Cervone, © Ask the Experts, LLC. ALL RIGHTS RESERVED. Originally published on November 11, 2012. Last updated on September 12, 2021.
Nutritional information is an approximation derived from a generic food database and is not a substitute for professional dietary advice.