If you want a comforting dinner that tastes like takeout without the fuss, this Slow Cooker Mongolian Beef hits the spot. It’s rich, savory, slightly sweet, and silky with just the right amount of ginger and garlic. The slow cooker does all the heavy lifting, giving you tender slices of beef in a glossy sauce.

Spoon it over rice, add a handful of green onions, and dinner feels special with almost no effort. It’s weeknight-friendly, but nice enough for company.

Why This Recipe Works

This recipe leans on a few simple techniques to build big flavor with minimal work. A cornstarch coating on the beef helps thicken the sauce as it cooks, while keeping the slices extra tender.

The combination of soy sauce, brown sugar, garlic, and ginger creates a balanced sauce that’s savory, sweet, and aromatic. Cooking low and slow lets the beef soak up the sauce without drying out. In the end, you get a silky, restaurant-style dish that’s easy to scale up.

What You’ll Need

• 2 pounds flank steak (or sirloin), thinly sliced against the grain
• 1/3 cup cornstarch
• 3/4 cup low-sodium soy sauce
• 1/2 cup brown sugar (light or dark)
• 1/2 cup beef broth (or water)
• 4 cloves garlic, minced
• 1 tablespoon fresh ginger, grated
• 1–2 tablespoons rice vinegar (to taste)
• 1–2 teaspoons toasted sesame oil
• 1/2 teaspoon red pepper flakes (optional, for heat)
• 2–3 green onions, sliced (plus more for garnish)
• 1–2 tablespoons neutral oil (optional, for searing)
• Sesame seeds (optional garnish)
• Cooked rice or noodles, for serving

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Instructions

1. Prep the beef: Pat the steak dry and slice it thinly against the grain. This helps the fibers break down and keeps the meat tender.
2. Coat with cornstarch: Add the slices to a bowl with the cornstarch and toss until evenly coated. Shake off any excess. This will help thicken the sauce later.
3. Optional sear: For deeper flavor, heat a skillet with a little oil over medium-high heat and quickly sear the beef in batches, 30–45 seconds per side. Don’t cook through—just brown. If you’re short on time, skip this step.
4. Make the sauce: In a bowl, whisk together soy sauce, brown sugar, beef broth, garlic, ginger, rice vinegar, sesame oil, and red pepper flakes if using.
5. Load the slow cooker: Add the beef (seared or not) to the slow cooker. Pour the sauce over the top and toss to coat.
6. Cook low and slow: Cover and cook on Low for 3–4 hours or on High for 2–2.5 hours, until the beef is tender and the sauce has thickened and turned glossy.
7. Adjust the sauce: If the sauce seems thin, mix 1 tablespoon cornstarch with 1 tablespoon cold water and stir it into the slow cooker. Cook 10–15 minutes more until thickened. If too thick, splash in more broth or water.
8. Finish and serve: Stir in the green onions during the last 10 minutes. Taste and adjust with a bit more vinegar or sugar if needed. Serve over rice or noodles and garnish with more green onions and sesame seeds.

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Keeping It Fresh

Store leftovers in an airtight container in the fridge for up to 4 days. The flavors deepen as it sits, and the sauce stays silky. Reheat gently on the stovetop over low heat, adding a splash of water to loosen the sauce if needed.

For longer storage, freeze in portions for up to 3 months. Thaw overnight in the fridge and reheat slowly to keep the texture tender.

Benefits of This Recipe

• Hands-off cooking: The slow cooker does most of the work, freeing you up for everything else.
• Takeout flavor at home: Big, bold taste with simple pantry ingredients.
• Budget-friendly: Flank or sirloin stretches far, and rice rounds it out.
• Meal prep ready: Holds up well in the fridge and freezer.
• Customizable: Easy to adjust sweetness, salt, and heat to your taste.

Pitfalls to Watch Out For

• Overcooking: Even in a slow cooker, sliced beef can overcook and turn stringy. Check at the earlier time mark.
• Too salty: Use low-sodium soy sauce. If it’s still salty, add water or broth and a touch more brown sugar or vinegar to balance.
• Watery sauce: Make sure the beef is coated in cornstarch, and don’t overcrowd if searing. Use a cornstarch slurry at the end if needed.
• Thick slices: Slice thinly against the grain. Thick pieces won’t tenderize as well.
• Skipping aromatics: Fresh garlic and ginger are key for that classic flavor.

Recipe Variations

• Veggie boost: Add sliced bell peppers, snap peas, or broccoli florets during the last 30–45 minutes so they stay crisp-tender.
• Gluten-free: Use tamari or certified gluten-free soy sauce and confirm all ingredients are GF.
• Lower sugar: Reduce brown sugar to 1/3 cup, then sweeten to taste at the end with a drizzle of honey if needed.
• Spicy version: Increase red pepper flakes, or add a spoonful of chili-garlic sauce or gochujang to the mix.
• Orange twist: Add 1–2 tablespoons orange zest and 1/4 cup orange juice for a bright, citrusy finish.
• Crispy edges: After slow cooking, spread the beef on a sheet pan and broil for 2–3 minutes to caramelize the sauce.
• Different cuts: Try thinly sliced chuck roast for a more economical option; cook on Low and lean on the cornstarch slurry at the end.

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FAQ

Can I make this without a slow cooker?

Yes.

Use a large skillet or Dutch oven. Sear the beef, add the sauce, then simmer on low for 20–30 minutes until tender and glossy, stirring occasionally. Keep the heat gentle and add water as needed.

Do I have to sear the beef?

No.

Searing adds depth, but the recipe works without it. If you skip it, make sure the beef is well coated in cornstarch and don’t overcook. The sauce will still thicken and taste great.

What should I serve with Mongolian beef?

Steamed jasmine rice is classic.

Brown rice, cauliflower rice, or lo mein noodles also work well. A side of steamed broccoli or stir-fried veggies rounds out the meal.

How do I keep the sauce from getting too sweet?

Start with the lower end of the sugar amount and taste at the end. Balance sweetness with a splash of rice vinegar or a squeeze of lime.

Low-sodium soy sauce also keeps the salt-sweet ratio in check.

Can I prep this ahead?

Absolutely. Slice and coat the beef, mix the sauce, and refrigerate separately up to 24 hours ahead. In the morning, combine in the slow cooker and set it to Low.

Dinner is ready when you are.

What if my sauce is too thick after chilling?

As it cools, the sauce thickens. When reheating, add a splash of water or broth and warm gently. Stir to bring it back to a silky consistency.

Is this recipe kid-friendly?

Yes, as written it leans sweet-savory.

If serving kids, skip the red pepper flakes and add them at the table for adults who want heat.

In Conclusion

Slow Cooker Mongolian Beef is the kind of recipe that makes weeknights feel easy and satisfying. With everyday ingredients and a short prep, you get tender beef in a glossy, flavorful sauce. It’s flexible, reliable, and great for meal prep.

Keep it simple with rice and green onions, or dress it up with veggies and garnish. Either way, it’s a keeper you’ll come back to again and again.