Mongolian Beef Slow Cooker

The aroma that filled my apartment when I first experimented with Mongolian beef in the slow cooker stopped me in my tracks. I'd been making stir-fry versions for years, but something about that low-and-slow transformation created depth I hadn't expected. My roommate poked her head in the kitchen, asking what smelled like we'd ordered takeout from the best spot in town. That evening became the benchmark for effortless comfort food that somehow tastes like it took all day.

Last winter, when my sister was recovering from surgery and needed meals she could easily reheat, I made a double batch of this. She texted me three days later confessing she'd eaten nothing else for days and was already asking when I'd make more. There's something about coming home to that smell waiting for you that makes even the longest days feel manageable.

Ingredients

• 2 pounds flank steak, thinly sliced: Flank offers the perfect balance of flavor and tenderness, especially when cut against the grain into thin strips that practically melt after hours in the slow cooker
• 3/4 cup low-sodium soy sauce: Starting with low-sodium lets you control the salt level since the sauce reduces and concentrates during cooking
• 3/4 cup brown sugar, packed: This creates that signature glossy finish and caramelizes beautifully, balancing the soy's saltiness with deep molasses notes
• 1/2 cup water: Essential for creating enough liquid to keep everything submerged and prevent burning during those long hours
• 1/4 cup hoisin sauce: The secret ingredient that adds complexity with its fermented bean paste sweetness and subtle five-spice undertones
• 1 tablespoon sesame oil: Toasted sesame oil delivers that unmistakable nutty aroma that signals you're about to eat something special
• 4 cloves garlic, minced: Fresh garlic transforms in the slow cooker, mellowing into something sweet and aromatic rather than sharp
• 1 tablespoon fresh ginger, grated: Fresh ginger brings brightness and heat that dried ginger simply cannot replicate in this dish
• 1/2 teaspoon crushed red pepper flakes: Even if you're heat-sensitive, include this small amount—it provides a gentle warmth that makes every other flavor pop
• 1/4 cup cornstarch: Creating a slurry at the end transforms the thin cooking liquid into that velvety, restaurant-quality coating
• 4 green onions, sliced: These add a fresh bite and vibrant color that cuts through the rich sauce
• 1 tablespoon toasted sesame seeds: The final garnish that adds crunch and makes the dish look as good as it tastes

Instructions

Whisk together your sauce base:

In a medium bowl, combine the soy sauce, brown sugar, water, hoisin sauce, sesame oil, garlic, ginger, and red pepper flakes until the sugar completely dissolves and everything is well incorporated.

Coat the beef with cornstarch:

Place your sliced flank steak in a large zip-top bag, add the cornstarch, seal it shut, and shake until every piece is lightly dusted, which helps create that velvety texture.

Combine everything in the slow cooker:

Transfer the cornstarch-coated beef to your slow cooker, pour the sauce mixture over the top, and give it a gentle stir until the beef is evenly covered in the liquid.

Let the slow cooker work its magic:

Cook on low for 4 hours, resisting the urge to lift the lid too often, until the beef is fork-tender and has absorbed all those incredible flavors.

Thicken the sauce to perfection:

During the last 30 minutes of cooking, whisk together the remaining cornstarch and cold water until smooth, then stir it into the slow cooker and let everything simmer until the sauce coats the back of a spoon.

Finish and serve with style:

Scoop the beef over steaming rice or noodles, then scatter the green onions and sesame seeds over the top for that final touch of freshness and crunch.

Save

This recipe became my go-to for new parents and friends recovering from illness because it's the kind of food that feels like a hug. I've learned that people remember the meals that showed up during their hardest days, and this one always seems to make it into their regular rotation afterward.

Make It Your Own

I've discovered that adding vegetables during the last hour of cooking transforms this into a complete meal without compromising the beef's texture. Bell peppers, snap peas, or even broccoli hold up beautifully and soak up that incredible sauce while maintaining their crunch.

The Rice Matters

After testing every rice variety in my pantry, jasmine rice emerged as the clear winner for pairing with Mongolian beef. Its natural floral sweetness and slightly sticky texture create the perfect foundation for catching every drop of that glossy sauce, though I'll admit brown rice works surprisingly well too if that's your preference.

Leftovers Get Even Better

Something magical happens overnight as the beef continues to absorb the sauce and the flavors deepen. I've started making extra just to ensure I have leftovers for lunch the next day, wrapped in a warm tortilla with some extra green onions for the most incredible beef wrap you've ever tasted.

• The sauce thickens even more in the refrigerator, so add a splash of water when reheating
• This freezes beautifully for up to three months if you want to meal prep for busy weeks
• Reheating on the stove with a gentle simmer brings the sauce back to life better than the microwave ever could

Save

There's something deeply satisfying about a recipe that delivers such impressive results with so little active effort. This Mongolian beef has earned its permanent spot in my regular rotation, and I suspect it will find its way into yours too.

Recipe FAQs

→ What type of beef works best for this dish?

Flank steak is ideal as it becomes tender when slow-cooked and shreds nicely. Slice it thinly across the grain for best results.

→ Can I make this gluten-free?

Yes, simply substitute tamari for soy sauce and use a gluten-free hoisin sauce. The cornstarch thickener is naturally gluten-free.

→ How do I prevent the beef from becoming tough?

Make sure to slice the flank steak thinly across the grain and cook on low for the full 4 hours. The slow cooking process breaks down the connective tissues.

→ What can I serve this with besides rice?

This pairs well with jasmine or basmati rice, or try it over steamed broccoli for a low-carb option. Noodles also work beautifully.

→ Can I add vegetables to this dish?

Yes, sliced carrots or bell peppers can be added with the beef for extra depth and nutrition. Add them at the beginning so they cook properly.