Imagine walking through your front door after a chaotic school run or a long shift and being greeted by the sweet, savory, and unmistakably aromatic scent of ginger and garlic. Your kitchen smells like the best neighborhood bistro, but you haven’t touched a pan in hours. This Easy Slow Cooker Mongolian Beef is my secret weapon for those nights when the calendar is full but the family is hungry.
We are skipping the greasy delivery and the high price tag for a dish that delivers tender, velvety ribbons of beef coated in a glossy, dark sauce that clings to every bite. If you can slice a steak and whisk a sauce, you have already mastered this recipe.
- Dietary: Can be Gluten-Free (use Tamari)
- Time: 15 mins prep, 4-5 hours cook
- Difficulty: Beginner-Friendly
- Cost per serving: ~$4.50
Why This Recipe Works
Traditional Mongolian beef relies on a technique called ‘velveting,’ where meat is quickly passed through hot oil to seal in moisture. In this slow cooker version, the cornstarch coating performs a double duty.
It creates a protective barrier around the flank steak, ensuring the fibers remain succulent during the long simmer rather than turning stringy. Using reduced-salt soy sauce allows us to control the seasoning perfectly, preventing the sauce from becoming an salt-bomb as it reduces. The brown sugar doesn’t just add sweetness; it creates the base for that iconic sticky glaze that defines the dish.
Key Ingredients & Notes
- 1 pound flank steak: Always slice against the grain to ensure the beef melts in your mouth rather than feeling chewy.
- 2-3 stalks green onion (or scallion): These provide a fresh, sharp bite that cuts through the richness of the beef.
- 1/4 cup cornstarch: This is the secret to the ‘velvety’ texture and a thick, luscious sauce.
- 1 tsp salt (to taste): Use kosher salt for a more controlled seasoning.
- 1 tsp black pepper (to taste): Freshly cracked pepper adds a subtle heat that balances the sugar.
- 3 teaspoons minced garlic: Garlic mellows as it slow-cooks, providing a deep, nutty foundation.
- 1/2 cup reduced salt soy sauce: This gives you the umami punch without the overwhelming sodium levels.
- 1 inch ginger: Freshly grated ginger provides a bright, zingy zing that ground ginger simply cannot match.
- 1/3 cup light brown sugar: This provides the classic molasses-tinged sweetness that caramelizes beautifully.
- 1/4 cup water: Just enough liquid to help the sauce emulsify without thinning it out too much.
- 2 tbsp vegetable oil: This helps distribute the heat and prevents the cornstarch-coated beef from clumping.
- 1 tbsp sesame oil: Add this for an earthy, toasted aroma that makes the dish smell professional.
- 1 tbsp sesame seeds: These add a delicate crunch and a beautiful visual finish.
Step-by-Step Instructions
Slice the flank steak into thin strips, ensuring you cut across the grain. Then, dice those strips into bite-sized cubes and move them into a large mixing bowl.
Season your beef generously with salt and pepper. Toss the meat with the cornstarch, mixing thoroughly until every piece is evenly coated. This might look a little messy, but that powdery coating is what makes the magic happen later.
Drizzle the vegetable oil into the bottom of your slow cooker and layer the beef inside. Don’t worry if the pieces overlap; the slow cooker handles it.
Whisk together the garlic, grated ginger, brown sugar, sesame oil, soy sauce, and water. Pour this liquid gold over the beef and give everything a quick stir to make sure the steak is well-acquainted with the sauce.
Cook on HIGH for 2 1/2 hours or on LOW for 4 to 5 hours. Your kitchen will start smelling incredible around the two-hour mark! When the timer dings, stir the mixture one last time to incorporate the thickened sauce.
Garnish with a heavy sprinkle of sesame seeds and those bright green onions. Serve it immediately over a steaming bed of jasmine rice or rice noodles.
Expert Tips for Success
To make slicing the beef easier, place the steak in the freezer for 20 minutes before cutting. The slight firmness allows you to get those restaurant-thin ribbons without the meat sliding around. If your sauce feels too thick after cooking, whisk in a tablespoon of warm water at a time until it reaches your desired consistency. To prevent the beef from sticking, ensure the slow cooker insert is lightly greased or use a slow cooker liner for an even faster cleanup.
Variations & Substitutions
If you want to make this Keto-friendly, swap the brown sugar for a monk fruit gold sweetener and use Xanthan gum in place of cornstarch (use only 1/2 teaspoon of Xanthan gum). If you find yourself without flank steak, sirloin tip or even chicken thighs work beautifully here. For a spicy kick, toss in a teaspoon of red pepper flakes or a squeeze of Sriracha during the final stir.
Frequently Asked Questions
You should thaw the beef completely before starting. Cornstarch won’t adhere to frozen meat, and the extra moisture from the ice will dilute your beautiful sauce, leaving it thin and watery.
Beef usually stays tough if it hasn’t cooked long enough or if it was sliced with the grain. If the timer is up and it’s not tender, give it another 30 minutes on high; every slow cooker heats slightly differently.
This beef actually tastes better the next day! Store it in an airtight container for up to 3 days. Reheat it gently on the stovetop with a splash of water to loosen the sauce back up.
Recipe updated in 2026 to reflect the most accurate timing and additional insights.
Slow Cooker Mongolian Beef for Busy Moms
Equipment
- Slow Cooker
- Mixing Bowl
- Whisk
- Chef's Knife
- Cutting Board
Ingredients
- 1 pound flank steak
- 2-3 stalks green onion or scallion
- 1/4 cup cornstarch
- 1 tsp salt to taste
- 1 tsp black pepper to taste
- 3 teaspoons minced garlic
- 1/2 cup reduced salt soy sauce
- 1 inch ginger
- 1/3 cup light brown sugar
- 1/4 cup water
- 2 tbsp vegetable oil
- 1 tbsp sesame oil
- 1 tbsp sesame seeds
Instructions
- Slice the flank steak against the grain into thin strips, then into cubes.
- Toss the beef with salt, pepper, and cornstarch until fully coated.
- Place vegetable oil and beef into the slow cooker.
- Whisk garlic, ginger, brown sugar, sesame oil, soy sauce, and water together and pour over beef.
- Cook on High for 2.5 hours or Low for 4-5 hours.
- Stir well and garnish with sesame seeds and green onions before serving.
Notes
- Freeze the beef for 20 minutes before slicing to get perfect thin strips.
- If the sauce is too thick, whisk in a tablespoon of warm water.
- Use a slow cooker liner for the fastest possible cleanup.
