This slow cooker 6-ingredient Mongolian beef is the kind of weeknight supper that practically makes itself and always gets a yes at my table. You literally toss cornstarch over raw flank steak right in the slow cooker, mix in just four more pantry-friendly ingredients, and let it simmer low and slow until the beef is fall-apart tender and coated in a glossy, savory-sweet sauce. It’s loosely inspired by the Mongolian beef you find at American Chinese restaurants, but simplified for busy home cooks who still want something a little special without a sink full of dishes.
I like to spoon this Mongolian beef over fluffy white rice, but brown rice or jasmine rice work just as well. Add some steamed broccoli, green beans, or a simple side salad to round out the plate and bring in some color. If you have kids who like to dip, serve extra sauce in a little bowl on the side or let them pile the beef into warm flour tortillas or over buttered egg noodles. A sprinkle of sliced green onions or sesame seeds on top makes it feel restaurant-fancy with almost no effort.
Slow Cooker Mongolian BeefServings: 6
Ingredients
2 pounds flank steak, thinly sliced against the grain
1/3 cup cornstarch
3/4 cup low-sodium soy sauce
1/2 cup packed brown sugar
1/2 cup beef broth (or water in a pinch)
4 cloves garlic, minced (or 1 1/2 teaspoons garlic powder)
Directions
Lay your flank steak on a cutting board and slice it thinly against the grain into bite-size strips. This helps the beef get extra tender as it cooks.
Place the raw flank steak strips directly into the bottom of your slow cooker, spreading them out so they’re in an even layer as much as possible.
Sprinkle the cornstarch evenly over the raw flank steak in the slow cooker. Use your hands or tongs to toss and coat the beef thoroughly so every piece has a light, even dusting of cornstarch. It should look like a close-up process shot: hands tossing cornstarch over the raw steak right in the slow cooker on the counter.
In a medium bowl, whisk together the soy sauce, brown sugar, beef broth, and minced garlic until the sugar is mostly dissolved and everything is well combined.
Pour the soy sauce mixture evenly over the cornstarch-coated beef in the slow cooker, gently stirring to make sure all the pieces are coated and there are no dry spots of cornstarch left.
Cover the slow cooker with the lid and cook on LOW for 4–5 hours, or until the beef is very tender and the sauce has thickened into a glossy, clingy consistency. If your slow cooker runs hot, start checking around 4 hours.
Once cooked, give the beef a good stir to break up any clumps and mix it well with the sauce. Taste and adjust the seasoning if needed by adding a splash more soy sauce for saltiness or a pinch more brown sugar for sweetness.
Serve the Mongolian beef hot over rice, noodles, or your favorite grain, spooning extra sauce over the top. If you like, garnish with sliced green onions or a sprinkle of sesame seeds before bringing it to the table.
Variations & Tips
For picky eaters, keep the sauce mild by using low-sodium soy sauce and starting with the listed amount of brown sugar; you can always pass extra soy sauce at the table for adults who like more punch. If your kids are iffy on garlic, use garlic powder instead of fresh so the flavor is softer and more familiar. To add vegetables right in the slow cooker, stir in 2 cups of fresh or frozen broccoli florets or sliced carrots during the last 45–60 minutes of cooking so they stay tender-crisp instead of mushy. For a little heat, whisk 1–2 teaspoons of sriracha or a pinch of red pepper flakes into the sauce before pouring it over the beef. If the sauce is thinner than you like at the end, ladle about 1/4 cup of hot cooking liquid into a small bowl, stir in 1 tablespoon of extra cornstarch until smooth, then stir that slurry back into the slow cooker and cook on HIGH for 15–20 minutes until thickened. You can also swap flank steak for thinly sliced sirloin or flat iron steak if that’s what you have on hand; just keep the slices thin so they get tender. Leftovers reheat well in a skillet with a splash of water or broth and make great next-day rice bowls or wraps for easy lunches.
