Sour Cream Portobello Flank Steak Crockpot Recipe Step-by-step instructions

Before you start

Before starting, pat the flank steak dry and slice it thinly against the grain. Clean the portobello mushrooms with a damp paper towel and slice them about 1/2-inch thick.

Peel the shallots and leave them whole or halve any large ones. Measure the sour cream and gravy mix. Have a 6-quart slow cooker ready. No need to brown the beef first — the slow cooker will do all the work.

Instructions

Layer and Set

1. 1Layer the Ingredients
   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.
   Look for The beef should cover the bottom, with mushrooms and shallots mounded on top.
   Tip No need to stir — layering keeps the beef from overcooking on the bottom.
2. 2Add the Sauce Base
   Dollop the sour cream over the mushrooms and shallots. Sprinkle the brown gravy mix evenly over the top. Do not stir.
   Look for The sour cream forms white dollops and the gravy mix dusts the surface.
   Tip Stirring now can make the sauce grainy; let the slow cooker do the work.

The raw ingredients are layered in the crockpot: beef on the bottom, mushrooms and shallots on top, and a dollop of sour cream with a dusting of gravy mix over everything.

The colors are distinct — red beef, brown mushrooms, ivory shallots, white sour cream, and dark gravy powder. The mixture looks rustic and promising, with no need to stir.

Slow Simmer

3. 3Cook on Low
   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.
   Look for The sauce will deepen to a mahogany color and the beef will shred easily.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Low heat is key — high heat can toughen the flank steak.
4. 4Check the Beef
   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.
   Look for The beef shreds easily and the sauce is thick and glossy.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip If the sauce is too thin, remove the lid and cook on high for 15 minutes.

After hours on low, the crockpot is bubbling gently. The sauce has turned a deep mahogany brown, and the aroma of beef, mushrooms, and onion fills the kitchen. The beef is visibly tender, and the sauce clings to the ingredients. The shallots are soft and translucent, and the mushrooms have absorbed the gravy.

Finish and Serve

5. 5Cook the Noodles
   While the beef rests, cook the egg noodles according to the package directions in salted boiling water. Drain and toss with butter.
   Look for Noodles are tender but still firm to the bite.
   Tip Cook the noodles just before serving so they don't get mushy.
6. 6Serve the Steak and Gravy
   Spoon the buttered noodles onto plates. Ladle the beef, mushrooms, shallots, and gravy over the top. Serve hot.
   Look for The gravy coats the noodles and the beef is glistening.
   Tip A crisp green salad on the side balances the richness.

The buttered noodles are piled on plates, and the steaming beef and gravy are ladled over the top. The sauce is thick and velvety, coating each strand of noodle. The beef shreds easily, the mushrooms are meaty, and the shallots are sweet. The plate is glossy, fragrant, and ready to eat.

Common mistakes

One common mistake is lifting the lid too often during cooking. Each time the lid is removed, heat escapes and adds 20 to 30 minutes to the cooking time. Another mistake is using a high heat setting, which can make the beef tough and cause the sour cream to curdle.

Stick to low heat and resist the urge to peek. Also, avoid stirring the ingredients at the start — the layering helps the flavors develop and prevents the sauce from becoming grainy.

How to tell it’s done

The dish is done when the beef is fork-tender and easily shreds apart. The internal temperature of the beef should reach at least 145°F (63°C) for food safety, though it will likely be higher after long cooking.

The sauce should be thick enough to coat the back of a spoon, and the mushrooms should be soft and glossy. Let the beef rest for at least 3 minutes before serving to allow the juices to redistribute.

• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest