Dinner · Part 3 of 3: Tips & recipe card

Sour Cream French Onion Flank Steak Crockpot Dinner Tips, FAQ & printable recipe

Name: Sour Cream French Onion Flank Steak Crockpot Dinner
Prep time: 10 min
Cook time: 8 h
Total time: 8 h 10 min
Cuisine: American
Ingredients: 2 lb flank steak, thinly sliced against the grain; 2 large Vidalia onions, thinly sliced; 1 can (10.5 oz) beef consommé; 1 cup sour cream; 1 oz brown gravy mix (dry); 12 oz egg noodles, cooked and buttered

By Clara Weller · Oct 28, 2026

Slow cooker sour cream French onion flank steak with creamy gravy

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

Tips for success

For the most tender beef, slice the flank steak as thin as possible—about 1/4 inch thick—and always cut against the grain. If the steak is too thick, it will take longer to become tender.

If you have time, sear the slices in a hot skillet with a little oil before adding them to the slow cooker; this adds a deep, caramelized flavor that enhances the whole dish.

To thicken the sauce further, remove the beef and onions with a slotted spoon, then whisk a cornstarch slurry (1 tablespoon cornstarch mixed with 2 tablespoons cold water) into the remaining liquid.

Simmer on high for 10 minutes until thickened. This is a great trick if you prefer a gravy that clings more heavily to the noodles.

Variations

Mushroom Addition: Add 8 oz sliced cremini mushrooms along with the onions. They will cook down and add an earthy depth that complements the beef and gravy beautifully.
Garlic Herb Twist: Stir in 2 minced garlic cloves and 1 teaspoon dried thyme with the onions. The garlic infuses the sauce with aromatic warmth, while thyme adds a subtle herbal note.
Spicy Kick: Add 1/2 teaspoon red pepper flakes or a dash of hot sauce to the consommé before pouring. The heat balances the creaminess and adds a gentle warmth.
Cheesy Topping: Sprinkle shredded Swiss or provolone cheese over the finished dish just before serving. The cheese melts into the gravy, adding a nutty, creamy richness.

Storage and make-ahead

Fridge: Store leftovers in an airtight container in the refrigerator for up to 4 days.
Freezer: Freeze the cooked beef and sauce in a freezer-safe container for up to 3 months. Thaw overnight in the refrigerator and reheat slowly on the stovetop.
Reheat: Reheat in a saucepan over medium-low heat, stirring occasionally, until hot and bubbling.

Store any leftovers in an airtight container in the refrigerator for up to 4 days. The flavors will meld and deepen overnight. Reheat gently in a saucepan over medium-low heat, adding a splash of beef broth or water if the sauce has thickened too much. Avoid microwaving on high, which can make the beef tough.

You can assemble the entire slow cooker the night before: layer the beef, onions, consommé, sour cream, and gravy mix in the insert, then cover and refrigerate.

In the morning, place the insert in the slow cooker base and cook on low as directed. You may need to add 30 minutes of cooking time since the ingredients are cold.

Serving ideas

Serve the sour cream French onion flank steak over a generous pile of buttered egg noodles, with the gravy spooned over the top.

A sprinkle of fresh parsley adds a pop of color and freshness, though it's optional. For a low-carb option, serve over cauliflower mash or roasted vegetables instead of noodles.

This dish also pairs well with a simple green salad dressed with vinaigrette to cut through the richness. Crusty bread is perfect for sopping up the extra gravy. For a heartier meal, add a side of steamed green beans or roasted asparagus. The leftovers are even better the next day, so make extra if you can.

Frequently asked questions

Can this recipe be made ahead of time?

Yes, the entire slow cooker can be assembled the night before and refrigerated. In the morning, place the insert in the slow cooker and cook on low as directed. The cooking time may need to be extended by about 30 minutes because the ingredients start cold. Leftovers also keep well in the refrigerator for up to 4 days.

Why does the sour cream sometimes curdle?

Sour cream can curdle if it is low-fat or if the heat is too high. Use full-fat sour cream and cook on low rather than high. Adding the sour cream at the beginning is fine, but if you are concerned, you can stir it in during the last 30 minutes of cooking. Also, avoid stirring too vigorously once it is added.

Can the flank steak be substituted with another cut?

Absolutely. Sirloin steak or chuck roast are excellent alternatives. Chuck roast is especially good because it becomes very tender with long cooking. Just make sure to slice it thinly against the grain, or cut it into chunks if using a roast. Adjust cooking time accordingly—chuck may need a bit longer.

Is it necessary to serve this over noodles?

No, the dish is delicious on its own, but the noodles help soak up the rich gravy. Mashed potatoes, rice, or crusty bread are also great options. For a lower-carb meal, serve over roasted vegetables or cauliflower mash. The gravy is the star, so any vehicle that absorbs it well works.

Can this be cooked on high instead of low?

Yes, you can cook it on high for 4 to 5 hours instead of low for 7 to 8 hours. The result will still be tender, but the meat may be slightly less fall-apart. For the best texture, low and slow is recommended. Always check that the beef reaches an internal temperature of at least 145°F (63°C) before serving.

Recipe card

Sour Cream French Onion Flank Steak Crockpot Dinner

Prep 10 minCook 8 hTotal 8 h 10 minServes 6

Ingredients

2 lb flank steak, thinly sliced against the grain
2 large Vidalia onions, thinly sliced
1 can (10.5 oz) beef consommé
1 cup sour cream
1 oz brown gravy mix (dry)
12 oz egg noodles, cooked and buttered

Instructions

Place the thinly sliced flank steak strips in the bottom of the slow cooker. Spread the slices evenly so they cover the bottom. Scatter the sliced Vidalia onions over the beef, then pour the beef consommé over everything. Use a spoon to gently press the onions down so they are mostly submerged in the liquid.
Dollop the sour cream over the top of the onion and consommé mixture. Sprinkle the dry brown gravy mix evenly over the surface. Do not stir; simply leave the ingredients layered as they are. This allows the flavors to meld during cooking.
Cover the slow cooker with the lid and set the heat to low. Cook for 7 to 8 hours, or until the beef is fork-tender and the onions are very soft. Avoid lifting the lid during the first few hours to keep the heat steady. Let it rest for 3 minutes before slicing.
After 7 to 8 hours, test the beef by inserting a fork into a strip. It should pull apart easily with little resistance. The onions should be translucent and melting into the sauce. If the beef is not yet tender, continue cooking for another 30 minutes and check again. Let it rest for 3 minutes before slicing.
Once the beef is tender, turn off the slow cooker. Let the meat rest in the sauce for at least 3 minutes before serving. This allows the juices to redistribute and ensures each bite is moist.
While the beef rests, bring a large pot of salted water to a boil. Add the egg noodles and cook according to package directions until al dente, usually 6 to 8 minutes. Drain well and toss with butter if desired.
Spoon the hot egg noodles onto serving plates or into a large serving bowl. Ladle the flank steak and onion mixture over the noodles, making sure to include plenty of the rich gravy. Serve immediately while hot. Let it rest for 3 minutes before slicing.

Contains: gluten, milk, eggs

Estimated nutrition per serving

Calories: 610
Protein: 45 g
Carbohydrates: 55 g
Fat: 22 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.