Ultimate Slow Cooker Mongolian Beef

The smell that filled my apartment that first gray Tuesday stopped me in my tracks. I had dumped everything into the slow cooker with zero expectations, basically hoping for edible dinner after a chaotic week at work. Four hours later, that glossy, caramelized sauce was clinging to every tender strip of beef like magic. My roommate actually came out of her room asking if I had ordered takeout.

I made this for my parents last month when they visited, and my dad kept asking what restaurant it was from. Watching him reach for seconds before anyone else had finished firsts was honestly so satisfying. My mom demanded the recipe before she even finished her first bite.

Ingredients

• 2 lbs flank steak thinly sliced against the grain: Cutting against the grain shortens muscle fibers for tenderness that practically falls apart
• 1 cup low sodium soy sauce: Regular soy sauce makes the final dish overwhelmingly salty
• 2/3 cup dark brown sugar packed: Molasses in dark brown sugar gives that gorgeous deep color and caramel notes
• 1/2 cup water: Prevents the sauce from becoming too thick as it reduces
• 1/4 cup hoisin sauce: Adds that authentic Chinese American takeout depth and slight sweetness
• 1/4 cup cornstarch: This coating trick is what makes restaurant beef so tender and silky
• 4 cloves garlic minced: Fresh garlic makes a difference here do not use jarred
• 1 tablespoon fresh ginger grated: Peeling ginger with a spoon wastes less of the good stuff
• 1/2 teaspoon crushed red pepper flakes: Add more if you like heat but this amount gives just a gentle warmth
• 2 tablespoons sesame oil: Toasted sesame oil has way more flavor than regular
• 4 green onions sliced: Save the green parts for garnish and use whites during cooking
• 2 teaspoons toasted sesame seeds: Toast them in a dry pan for 2 minutes for maximum flavor

Instructions

Coat the beef:

Toss sliced flank steak with cornstarch in a large bowl until every piece is evenly coated and feels slightly velvety.

Start the slow cooker:

Add the cornstarch coated beef to your slow cooker spreading it into an even layer.

Whisk the sauce:

Combine soy sauce, brown sugar, water, hoisin sauce, garlic, ginger, red pepper flakes, and sesame oil in a separate bowl until completely smooth.

Pour and coat:

Pour the sauce mixture over the beef and stir gently to coat every piece evenly.

Cook low and slow:

Cover and cook on low for 4 hours until the beef is fork tender and sauce has thickened beautifully.

Add green onions:

Stir in sliced green onions during the last 10 minutes of cooking so they stay bright and fresh.

Finish and serve:

Serve hot over steamed rice and garnish with extra green onions and toasted sesame seeds.

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This recipe has become my go to for potlucks because it travels so well and people always ask for the recipe. Last time I brought it to a friends house someone literally scraped the serving bowl clean.

Making It Gluten Free

Swapping tamari for soy sauce and finding a gluten free hoisin makes this completely safe for gluten sensitive friends. I have tested several brands and San J tamari never disappoints.

Adding Vegetables

Broccoli florets or snow peas added during the last 30 minutes turn this into a complete meal. Do not add them earlier or they will turn into mush.

Serving Suggestions

Jasmine rice soaks up that incredible sauce better than anything else but cauli rice works if you are watching carbs.

• Cucumbers on the side help balance the rich sweet sauce
• Make extra rice because the sauce is too good to waste
• Reheats beautifully with a splash of water

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There is something so satisfying about a meal that tastes like it came from a restaurant but required almost zero active cooking time.

Recipe FAQs

→ What cut of beef works best for this dish?

Flank steak is ideal as it becomes incredibly tender when slow-cooked. You can also use sirloin or skirt steak if preferred. The key is to slice the beef thinly against the grain for maximum tenderness.

→ Can I make this gluten-free?

Yes! Simply use tamari or certified gluten-free soy sauce and hoisin sauce. The cornstarch helps thicken the sauce, but if you need a gluten-free alternative, arrowroot powder works well too.

→ How can I add more vegetables?

Broccoli or snow peas can be added during the last 30 minutes of cooking. They'll cook through while retaining their crisp-tender texture and absorbing the delicious sauce.

→ What's the best way to serve this?

Serve hot over steamed jasmine or basmati rice. The sauce is perfect for coating rice, and the tender beef pairs beautifully with fresh vegetables on the side.

→ Can I make this ahead of time?

The beef actually tastes even better when reheated, as the flavors have more time to meld. You can prepare it a day in advance and reheat gently on the stovetop or in the microwave.