Slow Cooker Mongolian Beef – Tender, Saucy & Better Than Takeout

If you love the deep, savory-sweet flavor of your favorite Asian takeout dishes, this Slow Cooker Mongolian Beef recipe will quickly become a household favorite. Thinly sliced flank steak is simmered low and slow in a rich soy-garlic sauce, resulting in melt-in-your-mouth beef coated in a glossy, flavorful glaze.

This dish is the perfect balance of sweet, salty, and umami — with hints of garlic and ginger that elevate the sauce while letting the beef shine. Best of all, it’s incredibly easy: toss everything in the slow cooker and let it work its magic while you go about your day.

Ingredients Overview

Each ingredient in this recipe contributes to the beef’s deep flavor and tender texture.

Beef:

• Flank Steak or Sirloin – Thinly sliced against the grain, it becomes ultra-tender after slow cooking.

• Cornstarch – Coats the beef and thickens the sauce during cooking, giving it that signature glossy finish.

Sauce Base:

• Low-Sodium Soy Sauce – Provides deep umami flavor and saltiness without overpowering.

• Brown Sugar – Balances the salt with rich sweetness. Dark brown sugar adds even more depth.

• Garlic – Fresh minced garlic gives a bold, aromatic kick.

• Ginger – Adds warmth and complexity. Fresh is best, but ground works in a pinch.

• Water or Beef Broth – Helps form the sauce base and keeps things from getting too salty.

Add-Ins:

• Red Pepper Flakes – Optional for a touch of heat.

• Carrots or Bell Peppers – Optional, but great for adding color and nutrition.

• Green Onions – Added at the end for a fresh, oniony bite.

Tip: Prep everything the night before and refrigerate — then just pop it into the slow cooker in the morning.

Step-by-Step Instructions

1. Prepare the Beef

Slice 1.5 to 2 lbs of flank steak thinly against the grain (about ¼ inch thick). Toss in a large bowl with:

• ¼ cup cornstarch

• Ensure all pieces are evenly coated. Shake off excess.

Let sit for 10 minutes while you prep the sauce.

2. Make the Sauce

In a separate bowl, whisk together:

• ½ cup low-sodium soy sauce

• ½ cup brown sugar

• ½ cup water or beef broth

• 1 tbsp minced garlic

• 1 tsp fresh grated ginger

• Optional: ½ tsp red pepper flakes

Stir until sugar is dissolved.

3. Combine in the Slow Cooker

Add coated beef to the bottom of the slow cooker. Pour the sauce over the top and stir gently to coat the meat.

Optional Additions: Add sliced carrots or bell peppers here for extra flavor and texture.

4. Cook Low and Slow

Cover and cook:

• Low: 4–5 hours

• High: 2.5–3 hours

The beef should be tender and the sauce slightly thickened. If the sauce is too thin, mix 1 tbsp cornstarch with 2 tbsp cold water, stir it in, and cook for 15 more minutes on high.

5. Finish and Serve

Stir in chopped green onions right before serving.

Serve hot over:

• Steamed jasmine or basmati rice

• Noodles (like lo mein or rice noodles)

• Cauliflower rice or steamed broccoli for a low-carb version

Tips, Variations & Substitutions

• Use Skirt Steak or Sirloin: If you can’t find flank steak, either of these work well.

• Make it Spicier: Add more red pepper flakes or a dash of sriracha.

• Add Veggies: Toss in snap peas, mushrooms, or bell peppers during the last hour of cooking.

• Thicker Sauce: For a thicker glaze, remove the lid for the last 30 minutes to let moisture evaporate.

• No Cornstarch? Use arrowroot powder or flour, but the texture may vary slightly.

Serving Ideas & Occasions

This dish is comfort food at its best — warm, savory, and richly satisfying.

• Pair With:

  • White rice or fried rice

  • Steamed broccoli or bok choy

  • Pickled veggies or Asian cucumber salad

  • Egg rolls or dumplings for a full meal

• Perfect For:

  • Busy weeknight dinners

  • Casual entertaining

  • Meal prep (it reheats beautifully)

  • Freezer-friendly batch cooking

Nutritional & Health Notes

Slow Cooker Mongolian Beef can be adapted to your diet:

• High in Protein – Lean flank steak provides a hearty, satisfying meal.

• Gluten-Free Option – Use tamari or coconut aminos instead of soy sauce.

• Lower Sugar Version – Reduce brown sugar to ⅓ cup or use coconut sugar.

Estimated per serving (1 of 4–6, with rice):

• Calories: ~400–450

• Protein: 30–35g

• Carbs: 20–30g

• Fat: 15–20g

• Sodium: ~800–1000mg (adjust with low-sodium soy sauce)

FAQs

Q1: Can I make this ahead of time?
A1: Yes! You can prep the beef and sauce the night before. Store separately or together in the fridge, then cook the next day.

Q2: Can I freeze Mongolian beef?
A2: Absolutely. Store in freezer bags or containers for up to 3 months. Thaw in the fridge overnight and reheat on the stovetop.

Q3: What’s the best cut of beef to use?
A3: Flank steak is ideal, but skirt steak, sirloin, or even thinly sliced chuck can work with slightly longer cooking.

Q4: Can I double the recipe?
A4: Yes. Make sure not to overcrowd your slow cooker. Cook time may increase slightly depending on quantity.

Q5: How do I thicken the sauce more?
A5: Use a cornstarch slurry (1 tbsp cornstarch + 2 tbsp cold water) stirred in during the last 15–30 minutes on high.

Q6: Can I add vegetables?
A6: Yes! Add bell peppers, carrots, or broccoli during the last 30–60 minutes to keep them tender but not mushy.

Q7: Is this recipe keto-friendly?
A7: To make it low-carb, reduce the brown sugar and serve with cauliflower rice. Use tamari or coconut aminos for gluten-free and keto compatibility.

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