30-Minute Mongolian Beef Stir Fry (Better Than Takeout!)
Learn how to make sweet and spicy Mongolian beef stir fry with tender marinated flank steak cooked in one skillet. This easy homemade takeout recipe is full of flavor, quick to make, and perfect for a weeknight dinner.
Equipment
Ingredients
Beef Marinade
- 1 ½ lbs flank steak sliced ¼ inch, against the grain
- 2 tbsp coconut aminos or soy sauce
- 1 tbsp mirin
- 1 tbsp rice vinegar
- 1 tbsp brown sugar
- ¼ tsp salt
- ¼ tsp black pepper
- ½ tsp baking soda
- 2 tbsp cornstarch
Mongolian Sauce
- 3 tbsp coconut aminos or soy sauce
- 1 tbsp oyster sauce
- 1 tbsp mirin
- 2 tbsp brown sugar
- 1 tsp red pepper flakes
- ¼ cup water mixed with 1 tsp cornstarch to make cornstarch slurry
Stir Fry Ingredients
- 2 tbsp avocado oil or any neutral cooking oil
- 1 sweet onion sliced
- 5 garlic cloves minced
- 2 tbsp white parts of green onion minced
- ½ cup green parts of green onion chopped
For Serving
- cooked white rice
Instructions
- Start by slicing the flank steak against the grain into thin ¼-inch strips. In a mixing bowl, combine the steak with the marinade ingredients, tossing well to coat. Set aside to marinate while you prep the rest of the ingredients, or refrigerate for up to 3 hours ahead of time for extra flavor. Next, whisk together the sauce ingredients in a small bowl and set aside. Slice the sweet onion, mince the garlic and the white parts of the green onions, and chop the green tops of the green onions.
- Heat avocado oil in a large skillet over medium-high heat. Once the oil is hot, add the marinated flank steak in a single layer. Avoid overcrowding the pan—you may need to cook in batches for the best sear. Sear the beef for 2–3 minutes per side, until it’s cooked to your desired doneness and develops a nice char and caramelization. Transfer the cooked beef to a plate and set aside.
- In the same skillet, add the minced garlic and the white parts of the green onion. Sauté for 1–2 minutes, just until fragrant. Add the sliced sweet onion and continue cooking for about 5 minutes, until softened and lightly golden. If the skillet looks a little dry, add a touch more avocado oil as needed.
- Add the seared beef back into the skillet along with the prepared sauce and the green parts of the green onion. Stir well to combine, coating the beef and vegetables evenly. Let everything simmer for 1–2 minutes, just until the sauce slightly thickens and clings to the beef. Serve immediately over white rice.
Notes
Don’t skip the baking soda: It may seem like a small step, but baking soda helps tenderize the flank steak, keeping the beef soft and flavorful once cooked.
Cook in an even layer: Be sure not to overcrowd the pan. Cooking the beef in batches if needed ensures each piece gets a beautiful sear and caramelization, which adds incredible flavor.
Marinate for maximum flavor: If you have time, marinate the beef for up to 3 hours to deepen the flavor and tenderize the meat even further. Short on time? A quick 10–15 minute marinade will still give you delicious results.
Storage
If you have leftovers, store your Mongolian beef with flank steak in an airtight container in the refrigerator for up to 3 days. Reheat gently in a skillet over medium heat to keep the beef tender, or microwave in short intervals. Serve again with fresh rice, noodles, or stir-fried vegetables for a quick and satisfying meal.
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