Name: Slow Cooker Mongolian Beef Recipe
Prep time: 15 min
Cook time: PT-491958H29M7S
Total time: PT-491958H29M7S
Cuisine: Asian-Inspired
Ingredients: 2 lbs flank steak, thinly sliced against the grain; ¼ cup cornstarch; 1 tablespoon olive oil; 1 cup low-sodium soy sauce; ¾ cup brown sugar; 1 cup beef broth; 4 cloves garlic, minced; 2 teaspoons fresh ginger, grated (or 1 teaspoon ground ginger); ½ teaspoon black pepper; ½ teaspoon red pepper flakes (optional); 1 red bell pepper, sliced (optional); 4 green onions, sliced (for garnish); Sesame seeds (optional)

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If you love the rich, saucy goodness of takeout but crave something homemade and effortless, this Slow Cooker Mongolian Beef Recipe is going to be your new favorite. Tender, thinly sliced flank steak simmers low and slow in a sweet and savory garlic-ginger sauce, soaking up every bit of flavor in the crockpot. The result? Beef that’s melt-in-your-mouth tender with a glossy, irresistible sauce reminiscent of the best restaurant dishes—without the fuss or stress. Whether you’re feeding a family or meal prepping for the week, this easy recipe brings that classic Asian-inspired taste straight to your kitchen, all while you go about your day.

Ingredients You’ll Need

A clear white bowl filled with bright red sliced meat sits in the upper left corner on a white marbled surface. Around it, arranged in small clear glass bowls, are several ingredients: coarse black and white pepper, minced yellow garlic, minced light yellow ginger, a mound of white starch powder, a bowl of thin white sliced onions, a pile of light brown sugar, a dark brown soy sauce, yellow cooking oil, red dried chili slices, a small bowl of salt crystals, and fresh green scallions placed at the bottom right. The colors are vivid, with the red meat and chili slices contrasting with the white bowls and onions, all set against the white marbled textured background. Photo taken with an iphone --ar 4:5 --v 7

This Slow Cooker Mongolian Beef Recipe works its magic with just a handful of simple, pantry-friendly ingredients that come together beautifully. Each element adds something essential to the dish—whether it’s that signature sweetness, a touch of warmth, or a silky texture that clings deliciously to every slice of beef.

Flank steak (2 lbs): Thinly sliced against the grain for tender, juicy bites that soak up the sauce perfectly.
Cornstarch (¼ cup): This helps thicken the sauce naturally while giving the beef a slight crispness when seared.
Olive oil (1 tablespoon): Used for a quick sear to lock in the beef’s flavor before slow cooking.
Low-sodium soy sauce (1 cup): The salty umami base that balances the sweetness and aroma of the dish.
Brown sugar (¾ cup): Brings the signature caramelized sweetness that Mongolian beef is famous for.
Beef broth (1 cup): Adds depth and a savory richness to the sauce.
Garlic (4 cloves, minced): Fresh and fragrant, it infuses the beef with bold, aromatic flavor.
Ginger (2 teaspoons fresh grated or 1 teaspoon ground): Gives the dish a bright, slightly spicy kick that balances the sweetness.
Black pepper (½ teaspoon): Adds a subtle heat and enhances the savory notes.
Red pepper flakes (½ teaspoon, optional): For those who like a little gentle heat in their sauce.
Red bell pepper (1, sliced, optional): Adds a pop of color and a tender crunch when added towards the end.
Green onions (4, sliced): Fresh garnish to brighten each serving with a mild onion flavor.
Sesame seeds (optional): Toasted topping that adds a nutty finish and pretty presentation.

How to Make Slow Cooker Mongolian Beef Recipe

Step 1: Prep and Coat the Beef

Start by slicing your flank steak thinly, always cutting against the grain to guarantee tenderness once cooked. Toss these strips in cornstarch until each piece is nicely coated. This coating is a game-changer—it helps the sauce cling beautifully to every bite and thickens naturally during cooking.

Step 2: Optional Sear for Extra Flavor

Heat olive oil in a skillet over medium-high heat and quickly sear the coated beef just until it browns lightly on the edges. This step is optional but highly recommended if you want that extra depth of caramelized flavor that tastes like you spent hours on the stove.

Step 3: Layer in the Slow Cooker

Transfer the seared beef to your slow cooker. In a mixing bowl, whisk together soy sauce, brown sugar, beef broth, garlic, ginger, black pepper, and red pepper flakes to make a luscious, aromatic sauce. Pour this over the beef, gently stirring to ensure every slice is coated.

Step 4: Slow Cook to Perfection

Cover your slow cooker and cook on low for 5 to 6 hours or on high for 3 to 4 hours. The slow simmer allows the flavors to meld beautifully, and the beef becomes tender enough to melt in your mouth. If you’re using red bell peppers, add them in the final 30 minutes so they stay vibrant and slightly crisp.

Step 5: Final Garnish for Serving

Just before serving, sprinkle sliced green onions and sesame seeds on top for a fresh, colorful touch. This little garnish elevates the dish, making it look restaurant-worthy and adding that last layer of flavor and texture.

How to Serve Slow Cooker Mongolian Beef Recipe

A close-up view of a dark black bowl filled with rich, shiny brown beef strips covered in thick sauce. There are small light green chopped scallions sprinkled evenly on top of the beef. Some orange carrot shreds are mixed in with the meat. The beef looks tender and glossy, sitting in the sauce at the bottom of the bowl. A wooden spoon is partly visible, resting inside the bowl beneath the beef. The background is a white marbled texture. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

Green onions and sesame seeds are classic and simple garnishes that bring brightness and delicacy to the dish. Their crunch and fresh flavor balance the sweetness and richness of the sauce perfectly.

Side Dishes

Slow Cooker Mongolian Beef Recipe shines when served alongside fluffy steamed rice, garlic fried rice, or even tender noodles. The rice or noodles soak up that addictive sauce, turning every bite into comfort food bliss. For some greens, consider quick stir-fried broccoli or snap peas for a crisp contrast.

Creative Ways to Present

If you want to switch things up, serve this beef over crispy rice cakes or pile it into lettuce cups for a refreshing handheld option. Drizzle extra sauce over roasted vegetables or baked sweet potatoes for a tangy twist that brings new life to leftovers.

Make Ahead and Storage

Storing Leftovers

Once cooled, store leftover Slow Cooker Mongolian Beef Recipe in an airtight container in the refrigerator. It keeps well for up to four days and develops even deeper flavors over time.

Freezing

You can freeze this dish for longer storage—just portion it out into freezer-safe containers or bags. When frozen, it retains its texture and taste for up to two months, making it an excellent meal prep option for busy weeks.

Reheating

Reheat gently in a skillet over medium-low heat or in the microwave, adding a splash of water or broth if the sauce thickened too much. This keeps the sauce silky and the beef tender without drying it out.

FAQs

Can I use a different cut of beef for this recipe?

Absolutely! While flank steak is ideal for its tenderness and quick cooking time, you can also use skirt steak or sirloin, just be sure to slice thinly against the grain for best results.

Do I have to sear the beef before adding it to the slow cooker?

No, searing is optional but highly recommended because it adds a depth of flavor and helps lock in juices, making the beef taste richer and more caramelized.

How spicy is this Slow Cooker Mongolian Beef Recipe?

The recipe includes red pepper flakes for a mild kick, but you can adjust the heat to your liking by adding more flakes or omitting them completely for a milder dish.

Can I make this recipe gluten-free?

Yes! Just substitute the soy sauce with tamari or a gluten-free soy sauce alternative to keep the flavors authentic without gluten.

What should I serve this with for a low-carb option?

For a low-carb meal, swap rice or noodles for cauliflower rice or steamed vegetables like bok choy or broccoli to keep it light and satisfying.

Final Thoughts

I cannot recommend this Slow Cooker Mongolian Beef Recipe enough—it’s the perfect blend of ease, flavor, and comfort. Whether you’re new to slow cooker dishes or a seasoned pro, this recipe promises juicy, tender beef packed with irresistible Asian-inspired sauce and aroma. Next time you crave takeout, give this one a whirl at home; I’m sure you’ll love how effortless and delicious it feels.