Slow-cooked Mongolian beef is the kind of dinner that feels like a takeout splurge but comes together with almost no babysitting. I started making this when weekday evenings were a race against time: a few minutes of prep, a slow cooker doing the heavy lifting, and a glossy, caramelized sauce that clings to tender slices of beef. It’s sweet, savory, and slightly sticky — a family-friendly crowd-pleaser that scales easily for meal prep or guests.
Why you’ll love this dish
This slow cooker version turns a restaurant favorite into an effortless weeknight winner. The low-and-slow method breaks down flank steak into tender, forkable ribbons without the risk of overcooking. Benefits include:
- Hands-off cooking: prep in 10 minutes and let the cooker finish the work.
- Budget friendly: flank steak or similar cuts become meltingly tender.
- Kid-approved: sweet-savory sauce with a mild sesame note appeals to picky eaters.
- Great for meal prep: it reheats and freezes well, making lunches and dinners simple.
Perfect for busy weeknights, casual dinner parties, or when you want the comfort of takeout without the cost.
How this recipe comes together
- Coat thinly sliced beef in cornstarch to create a silky, thickened sauce and give the meat a slight crust.
- Combine toasted sesame oil, garlic, ginger, soy sauce, brown sugar, and water to form the sauce base.
- Slow-cook everything until the beef is tender and the sauce has concentrated.
- Finish with fresh green onions for brightness right before serving.
This quick overview sets expectations: minimal active time, one slow cooker, and a saucy, tender result after 2–5 hours depending on heat setting.
What you’ll need
- 1 1/2 pounds flank steak (thinly sliced against the grain) — slicing against the grain is crucial for tenderness.
- 1/4 cup cornstarch — helps thicken the sauce and gives the beef a silky coating.
- 1 tablespoon toasted sesame oil — adds warm, nutty flavor. Substitute neutral oil if needed, but add a splash of sesame for flavor.
- 1 teaspoon minced garlic — fresh tastes best; jarred works in a pinch.
- 1 teaspoon minced ginger — fresh or paste is fine.
- 1/2 cup low sodium soy sauce — controls saltiness. Use tamari for gluten-free.
- 1/3 cup brown sugar — balances the soy; use coconut sugar for a less refined option.
- 1/2 cup water — thins the sauce so it concentrates while cooking.
- 1/2 cup green onions (for garnish) — slice on the bias for visual appeal.
Optional notes: For a thicker final glaze, you can add a cornstarch slurry (1 tsp cornstarch + 1 tbsp water) at the end and simmer on HIGH for 15 minutes.
Step-by-step instructions
- Toss the thinly sliced flank steak with the cornstarch in a large bowl. Make sure every piece is lightly and evenly coated — this creates a glossy finish and helps the sauce cling.
- Transfer the coated steak to the slow cooker. Add the toasted sesame oil, minced garlic, minced ginger, low sodium soy sauce, brown sugar, and water. Stir gently to combine so the cornstarch stays distributed.
- Cover and cook on HIGH for 2–3 hours or LOW for 4–5 hours, until the beef is fork-tender and the sauce has thickened slightly. Avoid lifting the lid frequently; the slow cooker needs steady heat.
- Stir in the sliced green onions just before serving to preserve their color and mild crunch. Serve immediately over rice or noodles.
Best ways to enjoy it
- Serve over steamed jasmine rice for a classic pairing that soaks up the sauce.
- Toss with udon or lo mein noodles for a saucier noodle bowl.
- Add quick-blanched broccoli, snap peas, or bok choy for color and texture.
- Garnish with toasted sesame seeds, thinly sliced red chiles for heat, or a squeeze of lime to brighten the sauce.
Plate in shallow bowls so every bite gets sauce, meat, and optional veggies.
How to store & freeze
- Refrigerating: Cool to room temperature, then store in an airtight container for up to 3–4 days.
- Reheating: Gently reheat on the stovetop over low-medium heat with a splash of water (or broth) to loosen the sauce. Microwave in 1-minute bursts, stirring between, until hot.
- Freezing: Freeze in portioned, airtight containers for up to 3 months. Thaw overnight in the fridge before reheating.
Food safety: Don’t leave cooked beef at room temperature for more than two hours. When reheating, ensure it reaches 165°F (74°C) throughout.
Helpful cooking tips
- Slice the beef very thinly across the grain — partial freezing for 20–30 minutes makes this much easier.
- If you want more caramelization, remove cooked beef with a slotted spoon and reduce the sauce on HIGH for 10–15 minutes, then toss back.
- For a less sweet sauce, reduce the brown sugar by a tablespoon or two. Taste as you go.
- Use low sodium soy sauce to control salt; many ready-made sauces are already salty.
- If the sauce is too thin at the end, whisk a small cornstarch slurry and stir it in, then cook on HIGH for 10–15 minutes to thicken.
Recipe variations
- Gluten-free: swap soy sauce for tamari and check that your cornstarch is certified gluten-free.
- Spicy Mongolian beef: add 1–2 teaspoons chili garlic sauce or a sliced serrano pepper to the slow cooker.
- Chicken or pork version: thinly sliced boneless chicken thighs or pork shoulder work; reduce cook time (chicken on LOW 3–4 hours).
- Veg-forward: double the veggies (broccoli, carrots, bell pepper) and reduce beef for a lighter dish.
- Citrus twist: finish with a tablespoon of orange juice for a bright, slightly tangy note.
Common questions
Q: Can I use a different cut of beef?
A: Yes. Skirt steak or sirloin tip work well if sliced thinly across the grain. Tougher cuts like chuck will also become tender but may render more connective tissue and require slightly longer cooking.
Q: My sauce didn’t thicken — what went wrong?
A: Two common causes: too much liquid in the cooker or the cornstarch got diluted. Lift the lid near the end and switch to HIGH to reduce the sauce, or stir in a cornstarch slurry (1 tsp cornstarch + 1 tbsp cold water) and cook 10–15 minutes.
Q: Is this safe to make ahead for a dinner party?
A: Absolutely. Slow-cooker Mongolian beef reheats well. Finish the dish, cool it, refrigerate, then gently rewarm and freshen with green onions just before serving.
Q: How can I make it less sweet or lower in sodium?
A: Reduce brown sugar by 1–2 tablespoons and use low-sodium soy sauce. You can also add a splash of rice vinegar to balance sweetness.
Conclusion
If you want a low-effort dinner that delivers the tangy-sweet, glossy flavor of takeout at home, this slow cooker method is a reliable go-to. For another tested version and extra notes, see the original Slow Cooker Mongolian Beef recipe at Dinner at the Zoo: Slow Cooker Mongolian Beef recipe at Dinner at the Zoo.
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Slow Cooker Mongolian Beef
- Total Time: 190 minutes
- Yield: 4 servings
- Diet: Gluten Free (if using tamari)
Description
A tender and flavorful slow-cooked Mongolian beef dish that feels like takeout but is made effortlessly at home.
Ingredients
- 1 1/2 pounds 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, for garnish
Instructions
- Toss the thinly sliced flank steak with the cornstarch in a large bowl until lightly coated.
- Transfer the coated steak to the slow cooker. Add sesame oil, garlic, ginger, soy sauce, brown sugar, and water. Stir gently to combine.
- Cover and cook on HIGH for 2–3 hours or LOW for 4–5 hours, until beef is fork-tender and sauce has thickened slightly.
- Stir in sliced green onions just before serving and serve over rice or noodles.
Notes
For a thicker glaze, add a cornstarch slurry (1 tsp cornstarch + 1 tbsp water) at the end and simmer on HIGH for 15 minutes.
- Prep Time: 10 minutes
- Cook Time: 180 minutes
- Category: Main Course
- Method: Slow Cooking
- Cuisine: Asian