Slow Cooker Mongolian Beef

Tender strips of beef bathed in a sticky, savory-sweet sauce with notes of ginger and garlic – that’s the magic of Slow Cooker Mongolian Beef. This beloved Asian-inspired dish transforms into something truly extraordinary when prepared in a slow cooker, allowing the flavors to meld together while the beef becomes irresistibly tender. The combination of brown sugar, soy sauce, and aromatic spices creates a caramelized glaze that coats each piece perfectly. You’ll learn how to create this restaurant-quality dish with minimal effort, impressing family and friends with complex flavors that developed while you were free to go about your day.

Why You’ll Love This Recipe

Slow Cooker Mongolian Beef delivers incredible flavor with remarkably little hands-on time. The magic happens while you’re away, transforming simple ingredients into a meal that tastes like you spent hours in the kitchen. Unlike takeout versions that can be overly sweet or greasy, this homemade version balances sweet, savory, and umami perfectly.

The texture contrast is what makes this dish truly special – melt-in-your-mouth beef strips with a delightful chew, coated in that glossy, sticky sauce that clings to each bite. The slow cooking process allows the meat to absorb all those amazing flavors while breaking down the proteins for maximum tenderness.

Budget-conscious cooks will appreciate that this recipe uses flank steak or sirloin, cuts that become incredibly tender through slow cooking but cost significantly less than premium cuts. Plus, you’ll have leftovers that taste even better the next day as the flavors continue to develop overnight in the refrigerator.

Ingredients

For this delicious Slow Cooker Mongolian Beef, gather:

• 1½-2 pounds (680-900g) flank steak or sirloin, sliced against the grain into ¼-inch strips
• ¼ cup (32g) cornstarch
• 2 tablespoons vegetable oil
• ½ cup (100g) brown sugar (light or dark)
• ¾ cup (177ml) low-sodium soy sauce
• ¾ cup (177ml) water
• 2 tablespoons rice wine or dry sherry (optional)
• 1 tablespoon minced fresh ginger
• 4-6 garlic cloves, minced (about 2 tablespoons)
• ½ teaspoon red pepper flakes (adjust to taste)
• 4 green onions, sliced diagonally into 1-inch pieces
• 2 tablespoons toasted sesame seeds (for garnish)
• Cooked rice, for serving

The flank steak is the star here – be sure to slice it thin and against the grain for maximum tenderness. Low-sodium soy sauce allows you to control the saltiness, while fresh ginger and garlic provide that authentic aromatic foundation essential to Mongolian beef recipes in the slow cooker.

Pro Tips

Flash-freeze the beef: For the thinnest, most even slices, place your flank steak in the freezer for 20-30 minutes before slicing. This partial freezing firms up the meat just enough to make cutting those thin, uniform strips significantly easier.

Don’t skip the cornstarch: Coating the beef in cornstarch before adding it to the slow cooker serves two critical purposes. First, it creates a protective barrier that helps lock in moisture during the long cooking process. Second, it helps thicken the sauce to that perfect, glossy consistency that clings beautifully to the meat. For best results, toss the beef in cornstarch and let it sit for 5-10 minutes before proceeding.

Layer flavors with a quick sear: While this is technically an extra step, it’s worth the five minutes it takes. Quickly searing the cornstarch-coated beef in a hot pan before adding it to the slow cooker creates the Maillard reaction, which develops deep, complex flavors that simply can’t be achieved through slow cooking alone. This step takes your Slow Cooker Mongolian Beef from good to restaurant-quality.

Instructions

Step 1: Prepare the beef
Slice your flank steak against the grain into thin, ¼-inch strips. Place the strips in a large bowl and sprinkle with cornstarch. Toss thoroughly until each piece is lightly coated. Let the beef sit for about 10 minutes while you prepare the sauce ingredients.

Step 2: Optional sear (recommended)
Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat. Working in batches to avoid overcrowding, quickly sear the beef strips for about 1 minute per side until lightly browned. You’re not cooking them through, just developing flavor. Transfer the seared beef to your slow cooker.

Step 3: Prepare the sauce
In a medium bowl, whisk together the brown sugar, soy sauce, water, rice wine (if using), minced ginger, minced garlic, and red pepper flakes until the sugar is dissolved. Pour this mixture over the beef in the slow cooker, gently stirring to ensure all pieces are coated.

Step 4: Slow cook to perfection
Cover and cook on LOW for 6-7 hours or on HIGH for 3-4 hours. The beef should be tender but not falling apart. During the last 30 minutes of cooking, stir in half of the green onions, reserving the rest for garnish.

Step 5: Finish and serve
Once cooking is complete, the sauce should be thick and glossy. If it’s not quite thick enough, mix 1 tablespoon cornstarch with 2 tablespoons cold water to create a slurry, add it to the slow cooker, and cook on HIGH for an additional 15 minutes. Serve your Slow Cooker Mongolian Beef over hot rice, garnished with the remaining green onions and toasted sesame seeds.

Variations

Spicy Mongolian Beef: For heat lovers, amp up the spice level by doubling the red pepper flakes and adding 1-2 tablespoons of sriracha or your favorite chili paste to the sauce. The slow cooker will mellow the heat slightly while infusing the entire dish with a pleasant warmth that complements the sweet and savory components of traditional Mongolian beef in the slow cooker.

Vegetable-Loaded Version: Transform this into a complete one-pot meal by adding vegetables in the last 30-60 minutes of cooking (timing depends on your desired texture). Bell peppers, snow peas, broccoli florets, and sliced carrots all work beautifully. The vegetables will absorb the rich sauce while maintaining some texture, creating a more nutritionally balanced meal.

Keto-Friendly Adaptation: Replace the brown sugar with a brown sugar substitute and the cornstarch with xanthan gum (use about ½ teaspoon, mixed with the sauce ingredients). Serve over cauliflower rice instead of traditional rice for a low-carb version that maintains all the flavor of classic Slow Cooker Mongolian Beef.

Storage and Serving

Slow Cooker Mongolian Beef actually improves after a day in the refrigerator as the flavors continue to meld. Store leftovers in an airtight container for up to 4 days. For longer storage, freeze portions in freezer-safe containers for up to 3 months. Thaw overnight in the refrigerator before reheating gently on the stovetop or microwave with a splash of water to revive the sauce.

For serving, the classic presentation is over steamed white rice, which provides the perfect neutral canvas for the rich, flavorful sauce. For a lower-carb option, serve over cauliflower rice or alongside steamed vegetables.

Create a complete Asian-inspired feast by serving with simple steamed broccoli, vegetable potstickers, or a fresh cucumber salad with rice vinegar dressing. For a fun appetizer approach, serve small portions in lettuce cups topped with crispy wonton strips for a delightful texture contrast.

FAQs

Can I use different cuts of beef for Mongolian beef?
Yes! While flank steak is traditional, you can use sirloin, skirt steak, or even chuck roast (cut into thin strips). The key is slicing against the grain, regardless of which cut you choose. Tougher, more economical cuts actually work beautifully in Slow Cooker Mongolian Beef as the long cooking time breaks down the connective tissues.

Why is my sauce too thin?
This typically happens if there’s too much liquid released from the meat during cooking. Fix it by creating a cornstarch slurry (1 tablespoon cornstarch mixed with 2 tablespoons cold water) and stirring it into the slow cooker during the last 30 minutes of cooking time with the heat on HIGH.

Can I make this dish ahead of time?
Absolutely! In fact, the flavors improve overnight. Cook completely, refrigerate, and gently reheat when ready to serve. You can also prep all components the night before – slice the beef, mix the sauce, and store separately in the refrigerator, then combine everything in the slow cooker in the morning.

Is Mongolian beef actually from Mongolia?
Despite its name, Mongolian beef is not a traditional Mongolian dish but rather a creation of Chinese-American restaurants. The name likely refers to the cooking style reminiscent of Mongolian barbecue.

Can I add vegetables directly to the slow cooker?
Yes, but timing is crucial. Add hardy vegetables like carrots in the beginning, but add quick-cooking vegetables like bell peppers, snow peas, or broccoli only in the last 30-60 minutes to prevent them from becoming mushy.

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