Dinner · Part 3 of 3: Tips & recipe card

Slow Cooker Gruyère French Onion Flank Steak Tips, FAQ & printable recipe

Name: Slow Cooker Gruyère French Onion Flank Steak
Prep time: 10 min
Cook time: 6 h
Total time: 6 h 10 min
Cuisine: French-American
Ingredients: 2 lb flank steak, thinly sliced against the grain; 2 large Vidalia onions, thinly sliced; 1 can (10.5 oz) beef consommé; 8 oz cream cheese, softened; 1 cup shredded Gruyère cheese; Toasted garlic brioche slices, for serving

By Clara Weller · Oct 28, 2026

Slow cooker filled with tender flank steak and onions in a creamy Gruyère sauce, with steam rising

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

Tips for success

For the best flavor, use high-quality beef consommé and a good Gruyère. The consommé adds a depth that plain broth lacks, and the Gruyère brings a nutty complexity. If you prefer a sharper taste, use aged Gruyère.

The onions should be sliced thinly so they melt into the sauce; thick slices will remain chunky. Let the cream cheese come to room temperature before adding it, as this helps it melt smoothly.

To make the dish even richer, you can brown the flank steak in a hot skillet before adding it to the slow cooker. This adds a caramelized crust and extra savory notes. However, the recipe works perfectly without this step.

If you have leftovers, the sauce will thicken as it cools; add a splash of beef broth when reheating. Serve with extra toasted brioche to soak up every last bit of sauce.

Variations

Mushroom and Thyme: Add 8 oz sliced cremini mushrooms and 1 tsp dried thyme along with the onions. The mushrooms add earthy depth and soak up the sauce beautifully.
Spicy Kick: Stir in 1/2 tsp red pepper flakes or a minced jalapeño with the onions for a subtle heat that cuts through the richness.
Beer-Braised: Replace half the consommé with a dark beer, such as stout or porter, for a malty, slightly bitter note that complements the cheese.
Herb-Infused: Add a few sprigs of fresh rosemary and thyme to the slow cooker before cooking. Remove the sprigs before serving for a fragrant, savory aroma.

Storage and make-ahead

Fridge: Store in an airtight container in the fridge for up to 4 days. Reheat gently on the stovetop or microwave, adding a splash of broth if needed.
Freezer: Freeze in a freezer-safe 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 little beef broth to loosen the sauce if necessary.

Store leftovers in an airtight container in the refrigerator for up to 4 days. The sauce may thicken when chilled; add a little beef broth or water when reheating to restore the desired consistency.

This dish can be assembled the night before: layer the beef, onions, consommé, and cheeses in the slow cooker insert, cover, and refrigerate. In the morning, place the insert in the slow cooker and cook on low as directed. Add 30 minutes to the cooking time if starting from cold.

Serving ideas

Serve the beef and sauce over toasted garlic brioche for the classic French onion experience. The bread soaks up the rich sauce, making each bite satisfying.

For a heartier meal, spoon the mixture over mashed potatoes, egg noodles, or polenta. A simple green salad with a tangy vinaigrette balances the richness.

This dish is also delicious as a filling for sandwiches or tacos. Shred the beef and pile it onto crusty rolls with a bit of the sauce.

Top with extra Gruyère and broil until melted. For a low-carb option, serve over roasted vegetables or cauliflower rice. The sauce is so good you’ll want to use every last drop.

Frequently asked questions

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

Yes, skirt steak or sirloin strips work well, but adjust cooking time as needed. Flank steak is ideal because it becomes tender with long, slow cooking. Leaner cuts may dry out, so keep an eye on them.

Why does the sauce sometimes look curdled?

Curdling can happen if the cream cheese is added cold or if the heat is too high. Let the cream cheese soften before adding, and cook on low. Stir gently at the end to combine the sauce smoothly.

Can this be cooked on high instead of low?

Yes, but the texture may be less tender. If using high, cook for 3 to 4 hours and check the beef for doneness. Low heat is recommended for the best results.

What can be used instead of brioche for serving?

Sourdough, French bread, or even garlic bread are excellent substitutes. The key is to use a crusty bread that can soak up the sauce without falling apart.

How can the sauce be thickened if it’s too thin?

After cooking, remove the beef and onions, then simmer the sauce on the stovetop or on high in the slow cooker with the lid off for 15-20 minutes. Alternatively, mix 1 tbsp cornstarch with 2 tbsp water and stir in.

Recipe card

Slow Cooker Gruyère French Onion Flank Steak

Prep 10 minCook 6 hTotal 6 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
8 oz cream cheese, softened
1 cup shredded Gruyère cheese
Toasted garlic brioche slices, for serving

Instructions

Place the flank steak strips in the bottom of a 6-quart slow cooker. Scatter the sliced onions over the beef. Pour the beef consommé over everything. Add the softened cream cheese in spoonfuls and sprinkle with the shredded Gruyère. Do not stir.
Cover the slow cooker and cook on low for 6 to 8 hours, until the beef is fork-tender and the onions are meltingly soft. Do not lift the lid during the first 4 hours to keep the heat steady. Let it rest for 3 minutes before slicing.
After cooking, stir the sauce well to incorporate the melted cream cheese and Gruyère into the beef and onions. If the sauce seems thin, continue cooking uncovered on high for 15 to 20 minutes to reduce slightly.
Test a piece of beef with a fork; it should shred easily. If using an instant-read thermometer, insert it into the thickest piece of beef; it should read at least 145°F (63°C). Let the beef rest for 3 minutes before serving.
Ladle the hot beef and sauce over toasted garlic brioche slices on each plate. The bread will soak up the rich sauce. Serve immediately, with extra sauce spooned over the top.

Contains: gluten, milk, eggs

Estimated nutrition per serving

Calories: 620
Protein: 38 g
Carbohydrates: 28 g
Fat: 38 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.