Slow Cooker Gruyère French Onion Flank Steak Step-by-step instructions

Before you start

Before starting, thinly slice the flank steak against the grain into strips about 1/4-inch thick. Slice the onions thinly, and cut the cream cheese into cubes to help it melt faster. Have the beef consommé and shredded Gruyère measured and ready.

If you plan to serve with brioche, slice and toast it just before serving. There’s no need to brown the beef or sauté the onions—the slow cooker does all the work. Set out your slow cooker and make sure it’s clean and ready to go.

Instructions

Layer and Cook

1. 1Layer the Raw Ingredients
   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.
   Look for The slow cooker is full but not overflowing; the cheese sits on top.
   Tip Thin slicing against the grain ensures tender bites after long cooking.
2. 2Cover and Cook Low
   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.
   Look for The aroma of onions and beef fills the kitchen after a few hours.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Low and slow is key; high heat can make the beef tough.

At the end of this phase, the slow cooker is filled with raw beef, onions, consommé, and cheese. The cream cheese and Gruyère sit on top, looking like a creamy blanket.

After 6 to 8 hours on low, the kitchen smells of savory onions and beef. The cheese has melted into the liquid, and the beef is tender enough to shred with a fork. The sauce is thin but flavorful.

Finish and Thicken

3. 3Stir and Thicken the Sauce
   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.
   Look for The sauce is smooth, glossy, and coats the back of a spoon.
   Tip Stirring at the end brings the sauce together without breaking the beef.
4. 4Check the Beef for Doneness
   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.
   Look for The beef is tender enough to pull apart with a fork.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip The meat will continue to cook slightly as it rests.

After stirring, the sauce becomes smooth and glossy, with the cream cheese and Gruyère fully incorporated. The beef is tender and the onions are meltingly soft. If the sauce is too thin, it thickens slightly as it simmers. The texture should be rich and velvety, coating the meat and onions evenly.

Serve and Enjoy

5. 5Serve Over Toasted Brioche
   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.
   Look for The brioche is crisp at the edges and soaked with sauce underneath.
   Tip For a heartier meal, serve over mashed potatoes or egg noodles instead.

The final dish is a generous scoop of beef and onions in a creamy, savory sauce, served over toasted brioche. The brioche soaks up the sauce, becoming soft and flavorful. Each bite is a combination of tender beef, sweet onions, and rich cheese. The dish is best served hot, with extra sauce spooned over the top.

Common mistakes

One common mistake is using a lean cut like sirloin and cooking it too long, which can dry it out. Flank steak benefits from low, slow cooking to break down its fibers. Another pitfall is slicing the steak with the grain, which makes it tough; always slice against the grain.

Overfilling the slow cooker can cause uneven cooking, so stick to the recommended amounts. Finally, don’t be tempted to lift the lid during cooking—each peek releases heat and extends cooking time.

How to tell it’s done

The dish is done when the beef is fork-tender and easily shreds apart. The onions should be soft and translucent, and the sauce should be smooth and slightly thickened. If using a thermometer, the beef should read at least 145°F (63°C) in the thickest piece.

Let the beef rest for 3 minutes before serving to allow the juices to redistribute. The sauce should coat the back of a spoon; if it’s too thin, simmer uncovered for a few minutes to reduce.

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