Slow Cooker Mongolian Beef

Dive into a cozy weeknight dinner with Slow Cooker Mongolian Beef, where tender strips of beef bathed in a sticky-sweet ginger-garlic sauce effortlessly cook themselves in your slow cooker. Thinly sliced flank steak simmers in a rich blend of soy, brown sugar, and garlic until meltingly tender, then tossed with scallions for a warm, saucy feast over rice that’s perfect for busy evenings.

Key Ingredients

Gather these simple ingredients to build that signature sweet-savory sauce and melt-in-your-mouth beef texture:

• 1.5 pounds beef flank steak: Tender strips of beef that absorb the sweet-savory sauce and become melt-in-your-mouth soft.
• 1/4 cup cornstarch: Creates a light coating that crisps the beef edges when seared and thickens the sauce.
• 2 cups beef broth: Forms the liquid base, adding depth and umami to the Mongolian sauce as the beef cooks.
• 1/4 cup low sodium soy sauce: Provides rich savory seasoning and balances sweetness with its salty depth.
• 1/4 cup brown sugar: Delivers the classic sticky-sweet flavor that defines Mongolian beef.
• 1 tablespoon hoisin sauce: Brings a subtle sweet and tangy dimension to the sauce.
• 1 tablespoon rice vinegar: Cuts through richness with a bright, acidic note.
• 3 cloves garlic: Infuses the sauce with aromatic, pungent warmth.
• 1 teaspoon ginger: Adds fresh, zesty bite that complements the garlic and sugar.
• 2 teaspoons sesame oil: Lends a nutty aroma and rounds out the flavors.
• 1/2 teaspoon red pepper flakes: Introduces a gentle kick of heat that you can adjust to taste.
• 3 green onions: Stirred in at the end for a pop of color and mild onion flavor.
• 1 tablespoon vegetable oil: Used to sear the beef and lock in juices with a crisp exterior.
• 1 tablespoon water: Combined with cornstarch to form a slurry that thickens the final sauce.

How To Make Slow Cooker Mongolian Beef

Bringing Slow Cooker Mongolian Beef together is all about simple prep and letting the slow cooker do the heavy lifting. You’ll slice and coat the steak, quickly sear it for a flavorful crust, then bathe it in a fragrant sauce that slowly simmers into a glossy glaze. Finally, you’ll finish with a slurry to thicken and fresh scallions for that bright bite. Here’s the step-by-step:

1. Place the flank steak on a cutting board and, using a sharp knife, slice it thinly against the grain into even strips about 1/4-inch thick.

2. Transfer the steak strips to a large bowl and toss with 1/4 cup cornstarch until each piece is evenly coated, shaking off any excess.

3. Heat 1 tablespoon vegetable oil in a skillet over medium-high heat until shimmering. Sear the beef strips in batches until golden brown, about 1 to 2 minutes per side, then transfer them to the slow cooker.

4. In a medium bowl, whisk together 2 cups beef broth, 1/4 cup soy sauce, 1/4 cup brown sugar, 1 tablespoon hoisin sauce, 1 tablespoon rice vinegar, minced 3 cloves garlic, minced 1 teaspoon ginger, 2 teaspoons sesame oil, and 1/2 teaspoon red pepper flakes until smooth.

5. Pour the sauce mixture evenly over the seared beef in the slow cooker.

6. Cover and cook on LOW for 3 to 4 hours or HIGH for 1.5 to 2 hours until the beef is fork-tender.

7. In a small bowl, stir together 1 tablespoon cornstarch and 1 tablespoon water to form a smooth slurry.

8. About 15 minutes before the end of cooking time, stir the slurry into the slow cooker sauce to thicken it into a glossy glaze.

9. Slice the 3 green onions and stir them into the beef just before serving for a fresh pop of flavor.

10. Serve the Mongolian beef over steamed rice or noodles and dig in!

Serving Suggestions

This saucy, tender beef shines when paired thoughtfully—here’s how to serve it up like a pro:

• Pile it over steamed jasmine rice to let the glossy sauce soak in with each bite.
• Layer on a bed of freshly cooked chow mein noodles for an extra slurp-worthy meal.
• Sprinkle with extra sliced scallions and toasted sesame seeds for crunch and color.
• Add a side of steamed broccoli or baby bok choy to balance the rich flavors with bright, leafy greens.

Tips For Perfect Slow Cooker Mongolian Beef

These friendly tips will help you nail every aspect of this recipe, from prep to leftovers:

• For best slicing ease, partially freeze the steak for 30 minutes before cutting to get clean, even strips.
• Adjust red pepper flakes to dial in your preferred spice level, from mild warmth to fiery kick.
• Store any leftovers in an airtight container in the fridge for up to 3 days—perfect for next-day lunches.
• Feel free to substitute chicken or pork if you want a different protein; just slice and cook times accordingly.

How To Store It

Once you’ve enjoyed your Mongolian beef feast, proper storage keeps it tasting just as good later. Cool the dish to room temperature before packing, then choose one of these methods to maintain freshness:

• Refrigerate leftover beef and sauce in an airtight container for up to 3 days, ensuring the flavors stay vibrant.
• Freeze cooled portions in a freezer-safe container or heavy-duty bag for up to 2 months—label with the date.
• Thaw frozen servings overnight in the refrigerator before reheating to preserve texture.
• Reheat gently on the stovetop over low heat with a splash of water or beef broth to loosen the sauce and prevent drying out.

Frequently Asked Questions

Want quick answers? Here are some common questions about Slow Cooker Mongolian Beef:

• How can I ensure my beef slices don’t clump together when cooking?

Partially freeze the flank steak for about 30 minutes before slicing to firm it up, then cut thinly against the grain into even strips. Toss each strip thoroughly in cornstarch so they’re individually coated. This dry coating helps keep the strips separate when you sear and slow cook them.

• Can I substitute a different protein for beef in this slow cooker recipe?

Yes. Chicken thighs or pork tenderloin make excellent substitutes. Slice them into similar‐sized strips, then proceed with the same cornstarch coating and searing step. Reduce the slow-cooker HIGH time to 1 to 1.5 hours for chicken and 1.5 to 2 hours for pork to avoid overcooking.

• What’s the best technique for searing the beef before slow cooking?

Heat a tablespoon of vegetable oil in a skillet over medium-high heat until shimmering. Work in small batches so the pan stays hot, searing each side of the cornstarch-coated strips for about 1 to 2 minutes. Don’t overcrowd the pan—this ensures a quick, golden crust, locking in juices and building flavor before they go into the slow cooker.

• How do I properly thicken the sauce at the end of cooking?

About 15 minutes before the end of the cook time, whisk together a slurry of one tablespoon cornstarch and one tablespoon water until smooth. Stir the slurry into the slow cooker, cover, and let it finish cooking. As it heats, the sauce will thicken into a glossy glaze that coats the beef.

• Is there anything I can do ahead of time to streamline the cooking process?

Yes. You can slice and partially freeze the steak up to one day in advance and store it in the refrigerator until ready to coat and sear. You can also mince garlic and ginger, measure out soy sauce, brown sugar, hoisin, vinegar, sesame oil, and red pepper flakes into a bowl and refrigerate. That way, once the beef is seared you simply pour in the pre-mixed sauce.

• How should I store and reheat leftovers for best results?

Transfer leftovers to an airtight container and refrigerate for up to three days. Reheat gently over low heat on the stovetop, adding a splash of water or beef broth if the sauce has thickened too much. Stir occasionally until warmed through to prevent the beef from drying out.

• What’s the easiest way to adjust the spice level?

Tweak the red pepper flakes to your taste. Start with a pinch for mild heat, or increase up to half a teaspoon for a spicier kick. You can also omit them entirely for no heat, then serve sriracha or chili oil on the side so diners can customize their own plates.

What Makes This Special

Slow Cooker Mongolian Beef works its magic by marrying a foolproof slow-cooking method with bold Asian-inspired flavors that come alive in every bite. The cornstarch coating and quick sear locks in juices, while the sweet-salty sauce simmers into a silky glaze that clings to each tender strip. It’s fun, comforting, and utterly addictive—print this recipe and tuck it into your favorites for busy nights. If you try it out or have questions as you cook, drop a comment below or share feedback—I’m here to help!