Dinner · Part 3 of 3: Tips & recipe card

Sour Cream Portobello Flank Steak Crockpot Recipe Tips, FAQ & printable recipe

Name: Sour Cream Portobello Flank Steak Crockpot Recipe
Prep time: 10 min
Cook time: 6 h
Total time: 6 h 10 min
Cuisine: American
Ingredients: 2 lb flank steak, thinly sliced against the grain; 8 oz portobello mushrooms, thickly sliced; 6 shallots, peeled; 1 cup sour cream; 1 oz brown gravy mix; 12 oz egg noodles, cooked and buttered

By Clara Weller · Oct 28, 2026

Slow cooker full of braised flank steak, portobello mushrooms, and shallots in a rich sour cream gravy.

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

Tips for success

For the most tender flank steak, slice it as thinly as possible, about 1/4-inch thick. If the steak is very thick, you can pound it slightly with a meat mallet before slicing.

Always cut against the grain — the direction of the muscle fibers — to shorten the fibers and make the meat easier to chew.

To thicken the gravy at the end, remove the lid and cook on high for 15 to 20 minutes, stirring occasionally. If the sauce is too thick, add a few tablespoons of beef broth or water. For a richer flavor, use full-fat sour cream; low-fat versions can separate more easily during long cooking.

Variations

Add Red Wine: Deglaze the slow cooker with 1/2 cup dry red wine before adding the other ingredients. The wine adds depth and complexity to the sauce, making it taste even richer.
Herb-Infused: Add 2 sprigs of fresh thyme and 1 bay leaf along with the beef. Remove them before serving. The herbs lend an earthy, aromatic note that complements the mushrooms.
Spicy Kick: Stir 1 teaspoon of smoked paprika and 1/2 teaspoon of red pepper flakes into the gravy mix. This adds a subtle smoky heat that warms without overwhelming.
Veggie Boost: Add 2 cups of sliced cremini mushrooms and 1 cup of baby carrots along with the portobellos. They cook down into the gravy, adding sweetness and extra vegetables.

Storage and make-ahead

Fridge: Store leftovers in an airtight container in the fridge for up to 4 days. Keep noodles separate to avoid sogginess.
Freezer: Freeze the beef and gravy (without noodles) in a freezer-safe container for up to 3 months. Thaw overnight in the fridge.
Reheat: Reheat gently on the stovetop over medium-low heat, adding a splash of broth or water to loosen the sauce. Microwave in 30-second bursts, stirring between.

Store leftovers in an airtight container in the refrigerator for up to 4 days. The flavors will continue to meld, making the leftovers even more delicious.

Reheat gently on the stovetop or in the microwave, adding a splash of broth or water if the sauce has thickened too much. The noodles are best stored separately to prevent them from becoming soggy.

This recipe is ideal for making ahead. Assemble the ingredients in the slow cooker insert the night before, cover, and refrigerate overnight.

In the morning, place the insert in the slow cooker and cook on low as directed. You can also cook the full recipe, let it cool, and refrigerate for up to 3 days before reheating gently.

Serving ideas

Serve this stroganoff over a bed of warm buttered egg noodles, which soak up the rich gravy beautifully. The noodles provide a tender, comforting base that contrasts with the hearty beef and mushrooms.

For a lighter option, serve over mashed potatoes, rice, or even creamy polenta — all will catch the sauce just as well.

A crisp green salad with a bright vinaigrette is a perfect counterpoint to the richness of the dish. Steamed green beans or roasted asparagus also work well alongside. For a complete meal, add a slice of crusty bread to mop up any remaining gravy — it's too good to leave on the plate.

Frequently asked questions

Can this recipe be made with chicken instead of beef?

Yes, boneless chicken thighs or breasts can be substituted. Cook on low for 4 to 5 hours, until the chicken reaches 165°F (74°C). The cooking time will be shorter than for beef, so check early to avoid overcooking.

Why does the sour cream sometimes curdle?

Curdling can happen if the slow cooker is on high heat or if the sour cream is added too early and cooked too aggressively. Using full-fat sour cream and cooking on low helps prevent this. If curdling occurs, the sauce may look grainy but still tastes fine.

Can this be cooked on high instead of low?

Yes, but the beef may not become as tender. Cook on high for 3 to 4 hours, but check the beef at 3 hours. The sauce may also reduce more, so you might need to add a splash of broth.

What can be used instead of egg noodles?

Any pasta shape works well, such as fettuccine, pappardelle, or even wide egg noodles. For a gluten-free option, use rice noodles or gluten-free pasta. Mashed potatoes or rice also make excellent beds for the stroganoff.

How should leftovers be reheated?

Reheat gently on the stovetop over medium-low heat, adding a splash of beef broth or water to loosen the sauce. Alternatively, microwave in 30-second bursts, stirring between. Avoid boiling, as it can make the beef tough.

Recipe card

Sour Cream Portobello Flank Steak Crockpot Recipe

Prep 10 minCook 6 hTotal 6 h 10 minServes 6

Ingredients

2 lb flank steak, thinly sliced against the grain
8 oz portobello mushrooms, thickly sliced
6 shallots, peeled
1 cup sour cream
1 oz brown gravy mix
12 oz egg noodles, cooked and buttered

Instructions

Place the sliced flank steak strips in the bottom of a 6-quart slow cooker. Spread them into an even layer. Scatter the thickly sliced portobello mushrooms and peeled shallots over the beef.
Dollop the sour cream over the mushrooms and shallots. Sprinkle the brown gravy mix evenly over the top. Do not stir.
Cover the slow cooker and cook on low for 6 to 8 hours, until the beef is fork-tender and the sauce is thick and bubbling. Do not lift the lid during the first 4 hours. Let it rest for 3 minutes before slicing.
After 6 hours, check the beef. It should be very tender and pull apart with a fork. If not, continue cooking for up to 2 more hours. The internal temperature should reach at least 145°F (63°C). Let the beef rest for 3 minutes before serving.
While the beef rests, cook the egg noodles according to the package directions in salted boiling water. Drain and toss with butter.
Spoon the buttered noodles onto plates. Ladle the beef, mushrooms, shallots, and gravy over the top. Serve hot.

Contains: gluten, milk, eggs

Estimated nutrition per serving

Calories: 480
Protein: 35 g
Carbohydrates: 40 g
Fat: 20 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.