Slow Cooker Mongolian Beef

Absolutely dreamy, fall-apart tender beef bathed in a glossy, sweet-savory garlic ginger sauce that tastes just like your favorite takeout. This Slow Cooker Mongolian Beef is the very best kind of set-it-and-forget-it dinner.

You toss everything into the crockpot in minutes, walk away, and come back to luscious ribbons of steak coated in a silky sauce that begs for rice. It is a weeknight family favorite and a guaranteed crowd-pleaser for game night or casual gatherings.

Inspired by the classic restaurant dish, this streamlined version keeps the flavor big and the effort small. You will love the balance of caramelized brown sugar, umami soy, and a whisper of heat.

Why You'll Love This Recipe

• Hands-off cooking: Minimal prep and the slow cooker does the work while you do anything else.
• Takeout taste at home: Bold, glossy, sweet-savory sauce that rivals your favorite restaurant.
• Ultra tender beef: Light cornstarch coating and low, slow heat keep the steak melt-in-your-mouth.
• Flexible and forgiving: Works on Low or High, with easy swaps for dietary needs.
• Perfect for meal prep: Reheats beautifully and the sauce stays silky, not gummy.

Key Ingredients for Slow Cooker Mongolian Beef

See recipe card below for full list of measurements, ingredients, and instructions.

Flank Steak

This lean, flavorful cut becomes incredibly tender in the slow cooker and soaks up the sauce. Slice it thinly against the grain for the best bite. Skirt steak or sirloin tip will also work if flank is unavailable, though skirt is slightly richer and cooks faster. Trim any large seams of fat for a cleaner sauce.

Cornstarch

A light dusting of cornstarch on the beef protects the meat during cooking and helps the sauce cling for that signature glossy finish. Toss to coat evenly, shaking off excess so it does not clump. Arrowroot or potato starch are good gluten-free substitutes and will thicken a bit faster, so add them gradually.

Low-Sodium Soy Sauce

This is the umami backbone of the dish. Choose low-sodium to keep the sauce balanced since it reduces slightly as it cooks. Tamari is an excellent gluten-free alternative, and coconut aminos can be used for a slightly sweeter, less salty profile. If using regular soy, reduce added salt elsewhere.

Brown Sugar

Brown sugar gives the sauce its caramel notes and luscious body. Light brown sugar is classic, but dark brown sugar adds deeper molasses complexity. If you prefer less sweetness, reduce by a couple tablespoons and add a splash of rice vinegar to keep the flavor lively.

Fresh Garlic and Ginger

These aromatics make the Mongolian flavor pop. Grate or mince finely so they melt into the sauce. In a pinch, use bottled minced garlic and ginger paste, but fresh will taste brighter. Ground ginger works too at half the amount, though it will be slightly softer in flavor.

Instructions for Slow Cooker Mongolian Beef

See recipe card below for full list of measurements, ingredients, and instructions.

Slice and Velvet the Beef

Pat the flank steak dry and slice thinly against the grain, about 1/4 inch thick. Toss the slices with 1/4 cup cornstarch until lightly coated, then shake off any excess. This step keeps the meat tender and helps the sauce thicken beautifully.

Stir Together the Sauce

In a bowl, whisk soy sauce, broth, brown sugar, garlic, ginger, rice vinegar if using, and red pepper flakes until the sugar dissolves. Taste and adjust sweetness or heat to your preference.

Optional Sear for Extra Flavor

If you have 5 minutes, heat a large skillet over medium-high with the neutral oil. Sear the beef slices in batches for 30 to 60 seconds per side just to get a hint of color. Do not cook through. This adds depth but is optional.

Load the Slow Cooker

Add the beef to the slow cooker along with the carrots, if using. Pour the sauce over the top and toss gently to coat. Cover and cook on Low for 6 to 7 hours or on High for 3 to 4 hours, until the beef is tender but not shredded.

Thicken the Sauce

Stir together 2 tbsp cornstarch with 2 tbsp water to make a slurry. Stir the slurry into the slow cooker, add the green onions, and cook covered on High for 15 to 20 minutes until the sauce is glossy and slightly thick. Drizzle in the sesame oil and stir.

Finish and Serve

Taste and adjust seasoning, adding a splash more broth if you prefer a looser sauce. Serve the Mongolian beef over steamed rice and garnish with sesame seeds and extra sliced green onion.

Recipe Variations

Make It Spicy

Stir in 1 to 2 teaspoons of chili-garlic sauce or sambal with the slurry for a fiery kick. You can also add sliced fresh chilies in the last 30 minutes for bursts of heat.

Gluten-Free Friendly

Swap soy sauce for certified gluten-free tamari and use cornstarch or arrowroot. Keep an eye on the thickness since arrowroot sets faster. Everything else remains the same.

Lighter and Less Sweet

Reduce brown sugar to 1/3 cup and add 2 to 3 teaspoons rice vinegar for brightness. The sauce will be more savory-forward with a clean finish.

Veggie-Forward

Double the carrots and add sliced bell peppers or broccoli florets in the last 45 minutes so they stay crisp-tender. Mushrooms are great too and soak up the sauce.

Different Protein

Try thinly sliced chicken thigh or pork tenderloin. Cooking time will be a bit shorter, so check for tenderness at the 2 1/2 to 3 hour mark on High.

Serving Suggestions

Serve Slow Cooker Mongolian Beef over fluffy jasmine or basmati rice to catch all that glossy sauce. Add a side of quick garlicky sautéed green beans or steamed broccoli for color and crunch. Finish with sesame seeds, extra green onion, and a squeeze of lime for brightness.

Storage and Reheating

Refrigerate leftovers in an airtight container for up to 4 days. Reheat gently on the stovetop over medium-low heat, adding a splash of water to loosen the sauce, or microwave in 45 second bursts, stirring between each. Freeze in a freezer-safe container for up to 3 months. Thaw overnight in the fridge, then reheat as above. If the sauce seems thin after thawing, add a small cornstarch slurry and simmer briefly to restore the gloss.

Frequently Asked Questions About Slow Cooker Mongolian Beef (FAQ)

Q: Can I use a different cut of beef besides flank steak?
A: Yes. Sirloin, flat iron, or thinly sliced chuck roast all work well. Aim for thin slices against the grain and adjust cooking time as fattier cuts like chuck may need a bit longer on Low.

Q: Do I have to sear the beef before slow cooking?
A: No. Searing is optional and adds a touch of caramelized flavor, but the dish is still delicious without it. If you skip searing, be sure to coat the beef evenly in cornstarch for the best texture.

Q: How do I prevent the sauce from getting too sweet or too salty?
A: Use low-sodium soy, measure the brown sugar, and taste the sauce base before cooking. For less sweetness, reduce sugar slightly and add a splash of rice vinegar. If too salty, add a bit more broth and a pinch of sugar to rebalance.

Q: Can I make this ahead for meal prep?
A: Absolutely. Slice and coat the beef, mix the sauce, and refrigerate them separately up to 24 hours. Combine in the slow cooker when ready. Cooked leftovers reheat beautifully and are great for quick lunches.

This Slow Cooker Mongolian Beef delivers maximum flavor with minimal effort, perfect for busy nights and satisfying cravings. Give it a try, then leave a comment and rating to let me know how it turned out in your kitchen.