Name: Slow Cooker Mongolian Beef
Prep time: 10 min
Cook time: 4 h
Total time: 4 h 10 min
Cuisine: Chinese-American
Ingredients: 1 1/2 lbs flank steak, thinly sliced against the grain; 1/4 cup cornstarch; 1 tbsp toasted sesame oil; 1 tsp minced garlic; 1 tsp minced ginger; 1/2 cup low-sodium soy sauce; 1/3 cup brown sugar; 1/2 cup water; 1/2 cup green onions, cut into 1/2-inch pieces

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Tender, flavorful Mongolian beef made effortlessly in the slow cooker. Thinly sliced flank steak simmers in a savory-sweet soy, garlic, and ginger sauce until melt-in-your-mouth, then finishes with fresh green onions.

Slow Cooker Mongolian Beef

Why You’ll Love This Recipe

Set-it-and-forget-it slow cooker convenience
Classic takeout flavor with simple pantry ingredients
Ultra-tender beef in a glossy, spoon-coating sauce
Easy to scale for meal prep and leftovers
Family-friendly and perfect over rice or noodles

ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

1 1/2 lbs flank steak, thinly sliced against the grain
1/4 cup cornstarch
1 tablespoon toasted sesame oil
1 teaspoon minced garlic
1 teaspoon minced ginger
1/2 cup low-sodium soy sauce
1/3 cup brown sugar
1/2 cup water
1/2 cup green onions, cut into 1/2-inch pieces

directions

Place the sliced flank steak in a bowl with cornstarch; toss to evenly coat.
Add the coated beef to the slow cooker.
In a small bowl, whisk sesame oil, garlic, ginger, soy sauce, brown sugar, and water. Pour over the beef and stir to coat.
Cover and cook on HIGH for 2–3 hours or on LOW for 4–5 hours, until the beef is tender.
Stir in the green onions just before serving.

Servings and timing

Servings: 6
Prep Time: 10 minutes
Cook Time: 4 hours (on LOW)
Total Time: ~4 hours 10 minutes
Nutrition (per serving): Calories 308, Carbohydrates 23g, Protein 30g, Fat 9g, Saturated Fat 3g, Cholesterol 81mg, Sodium 629mg, Potassium 557mg, Sugar 14g, Vitamin A 100 IU, Vitamin C 1.9mg, Calcium 52mg, Iron 2.9mg

Variations

Swap protein: use thinly sliced chicken thigh or firm tofu cubes (press well)
Veg boost: add broccoli florets or snap peas in the last 30 minutes on LOW
Less sweet: reduce brown sugar to 1/4 cup for a more savory profile
Extra heat: add red pepper flakes or a diced fresh chili with the sauce
Thicker sauce: stir 1–2 additional teaspoons cornstarch into 2 tablespoons cold water; add and cook 10 minutes on HIGH

storage/reheating

Refrigerate in an airtight container up to 4 days
Freeze up to 2 months; thaw overnight in the refrigerator
Reheat gently on the stovetop over low heat with a splash of water to loosen the sauce, or microwave in short intervals, stirring between bursts

FAQs

Can I slice the beef ahead of time?

Yes. Slice up to 24 hours in advance; keep refrigerated and pat dry before tossing with cornstarch.

What cut of beef works best?

Flank steak is ideal, but sirloin, skirt, or thinly sliced round can also work—adjust cook time to prevent drying.

Do I have to coat the beef in cornstarch?

It helps protect the meat and naturally thickens the sauce. Skipping it will yield a thinner sauce.

Can I cook this on HIGH only?

Yes, 2–3 hours on HIGH produces tender results; check at 2 hours to prevent overcooking.

My sauce is too thin—how do I fix it?

Stir together 1 teaspoon cornstarch with 2 tablespoons cold water; add to the slow cooker and cook on HIGH for 10–15 minutes.

Is this recipe very sweet?

It’s balanced sweet-savory. For less sweetness, reduce brown sugar or increase soy sauce slightly to taste.

Can I add vegetables from the start?

Hardier veggies like carrots can go in early; quick-cooking ones (broccoli, snap peas) should be added in the last 20–30 minutes.

What should I serve it with?

Steamed jasmine rice, brown rice, cauliflower rice, or lo mein-style noodles are all great choices.

How thin should I slice the beef?

About 1/4-inch thick, cut against the grain for tenderness.

Can I make it gluten-free?

Use gluten-free soy sauce or tamari and ensure your cornstarch is certified gluten-free.

Conclusion

Slow cooker Mongolian beef delivers takeout-style flavor with minimal effort. With tender slices of beef, a glossy soy-garlic-ginger sauce, and a quick finish of green onions, it’s a reliable weeknight favorite that’s perfect for meal prep and easy to customize.