Dinner · Part 3 of 3: Tips & recipe card

Crockpot Portobello Dijon Cream Beef Roast Tips, FAQ & printable recipe

Name: Crockpot Portobello Dijon Cream Beef Roast
Prep time: 10 min
Cook time: 8 h
Total time: 8 h 20 min
Cuisine: American
Ingredients: 3 1/2 lb beef bottom round roast; 8 oz portobello mushroom caps, thickly sliced; 2 tbsp minced garlic; 1/2 cup sour cream; 1/4 cup whole-grain Dijon mustard; 1 cup au jus sauce; 1 tsp kosher salt; 1/2 tsp black pepper; Steamed white rice, for serving

By Clara Weller · Oct 28, 2026

Slow cooker beef roast with portobello mushrooms and creamy Dijon sauce, ready to serve

Prep: 10 min
Cook: 8 h
Total: 8 h 20 min
Serves: 6

Includes 10 min resting

Tips for success

For the best flavor, use whole-grain Dijon mustard—the seeds add a pleasant pop of texture and a milder heat than smooth mustard.

If you only have smooth, that's fine; just reduce the amount slightly and add a pinch of mustard powder to compensate. Taste the sauce before serving and adjust seasoning with salt and pepper.

The sauce will be thin when the roast is done. To thicken it, remove the beef and mushrooms, then whisk a slurry of cornstarch and cold water into the sauce and simmer on the stovetop until it thickens.

Alternatively, use an immersion blender to puree some of the mushrooms into the sauce for a naturally thicker gravy.

Variations

Herb Infusion: Add 2 sprigs of fresh thyme and 1 sprig of rosemary to the slow cooker along with the mushrooms. Remove the herb stems before shredding the beef. The herbs add an earthy, aromatic note that complements the mushrooms.
Spicy Kick: Stir 1/2 teaspoon of red pepper flakes or a minced chipotle pepper in adobo sauce into the sour cream mixture. This adds a subtle heat that balances the creamy sauce. Adjust the amount to taste.
Vegetable Boost: Layer 2 cups of baby carrots and 2 stalks of celery, chopped, at the bottom of the slow cooker before adding the roast. The vegetables will cook in the sauce and become tender, adding extra body and flavor to the dish.
Dairy-Free Option: Substitute the sour cream with a dairy-free sour cream alternative or full-fat coconut yogurt. Use a dairy-free Dijon mustard (most are) and check the au jus label for dairy. The sauce will be slightly different but still creamy and delicious.

Storage and make-ahead

Fridge: Store leftover roast and sauce in an airtight container in the refrigerator for up to 4 days. Reheat gently, adding a splash of broth if needed.
Freezer: Freeze in an airtight container for up to 3 months. Thaw overnight in the refrigerator before reheating.
Reheat: Reheat in a saucepan over medium-low heat, stirring occasionally, until hot. Add a splash of beef broth or water if the sauce has thickened.

Leftover roast and sauce can be stored in an airtight container in the refrigerator for up to 4 days.

Reheat gently on the stovetop or in the microwave, adding a splash of beef broth if the sauce has thickened too much. The flavors often improve after a day in the fridge.

This recipe is perfect for making ahead. Assemble the slow cooker insert the night before, cover, and refrigerate.

In the morning, place the insert in the slow cooker and cook as directed. You can also cook the roast a day ahead, shred it, and reheat gently with the sauce before serving.

Serving ideas

Serve the shredded beef and mushrooms over steamed white rice, egg noodles, or mashed potatoes. The creamy Dijon sauce is delicious spooned over the top. A side of green beans or a simple green salad balances the richness of the dish.

Leftovers make fantastic sandwiches—pile the beef on a toasted bun with a little extra sauce. The roast also freezes well; portion it into airtight containers and freeze for up to 3 months. Thaw overnight in the refrigerator and reheat gently.

Frequently asked questions

Can this recipe be made in an Instant Pot or pressure cooker?

Yes, but the cooking time changes. Sear the roast on sauté mode, then add the remaining ingredients. Cook on high pressure for about 60 minutes for a 3.5-pound roast, then let the pressure release naturally for 15 minutes. Check for tenderness and cook longer if needed.

Why is the sauce separating or curdling?

Sour cream can curdle if the heat is too high or if it's added too early. This recipe uses low heat, but if the sauce separates, it's still safe to eat. To prevent it, ensure the sour cream is at room temperature and stir it in gently. If it does curdle, whisk in a teaspoon of Dijon mustard to help emulsify.

Can this recipe be made with a different cut of beef?

Absolutely. Chuck roast or brisket are excellent substitutes because they have more marbling and become very tender. Avoid lean cuts like sirloin tip, which can dry out during long cooking. Adjust the cooking time as needed—chuck may take slightly longer.

Can the leftovers be frozen?

Yes, this dish freezes well. Cool the leftovers completely, then transfer to an airtight container or freezer-safe bag. Freeze for up to 3 months. Thaw overnight in the refrigerator and reheat gently on the stovetop or microwave.

What can be used instead of au jus sauce?

If you don't have au jus, use beef broth or beef stock. Add a teaspoon of Worcestershire sauce (omit if you have a fish allergy) and a pinch of onion powder to mimic the flavor. Alternatively, use a store-bought au jus packet mixed with water.

Recipe card

Crockpot Portobello Dijon Cream Beef Roast

Prep 10 minCook 8 hRest 10 minTotal 8 h 20 minServes 6

Ingredients

3 1/2 lb beef bottom round roast
8 oz portobello mushroom caps, thickly sliced
2 tbsp minced garlic
1/2 cup sour cream
1/4 cup whole-grain Dijon mustard
1 cup au jus sauce
1 tsp kosher salt
1/2 tsp black pepper
Steamed white rice, for serving

Instructions

Place the beef bottom round roast in the center of the slow cooker insert. Season all sides with salt and pepper. If the roast is larger than the insert, trim it to fit without crowding.
Scatter the sliced portobello mushrooms over and around the roast. Sprinkle the minced garlic evenly over the top. No need to stir—layering keeps the flavors distinct.
In a small bowl, stir together the sour cream and whole-grain Dijon mustard until smooth. Dollop the mixture over the roast and mushrooms. Pour the au jus along the side of the insert, not directly over the top.
Cover the slow cooker and cook on low for 8 to 10 hours, until the beef is fork-tender and easily shreds. Avoid opening the lid during cooking to keep the heat steady. Let it rest for 3 minutes before slicing.
After 8 hours, test the roast with a fork. It should pull apart easily with no resistance. If not, continue cooking for another 30 to 60 minutes. Let it rest for 3 minutes before slicing.
Turn off the slow cooker. Remove the roast to a cutting board and let it rest for at least 10 minutes. This allows the juices to redistribute.
Using two forks, shred the beef into bite-sized pieces. Return the shredded beef to the slow cooker and stir gently into the sauce.
Spoon the shredded beef and mushroom mixture over steamed white rice. Ladle extra sauce over the top. Serve hot.

Contains: milk, mustard

Estimated nutrition per serving

Calories: 520
Protein: 48 g
Carbohydrates: 12 g
Fat: 30 g

Automatic estimate from the ingredient list, not laboratory-verified.

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This recipe is based on a short cooking video and is published under the pen name Clara Weller. It was checked before publication, but errors can slip through. Nutrition, when shown, is an estimate. Read more in our editorial policy and on our food safety page.