Keto Mongolian Beef Stir Fry

May 21, 2025

This website contains affiliate links. As an Amazon Associate, I earn from qualifying purchases.

This keto Mongolian beef stir fry is a low-carb take on the takeout favorite. Thin slices of flank steak get a quick sear, then toss in a glossy garlic and ginger sauce that is sweet and salty without any sugar.

It cooks fast, so have everything sliced and measured before you turn on the stove. Spoon it over steamed broccoli, cauliflower rice, or shirataki noodles for a keto-friendly bowl. The recipe serves 4.

Why This Keto Mongolian Beef Works

Restaurant Mongolian beef usually gets its sweetness from lots of brown sugar and its thick sauce from cornstarch. This version swaps in brown erythritol or monk fruit for the sweetness and an optional pinch of xanthan gum to thicken. You keep the flavor and lose most of the carbs.

The steak stays tender for two reasons. It is sliced thin against the grain, which shortens the tough muscle fibers. And it is seared fast over high heat and pulled from the pan before the sauce goes in, so it does not overcook. The optional baking soda step, called velveting, makes it even softer, like the beef you get at a good Chinese restaurant.

Ingredients and Easy Swaps

Flank steak (1 pound): Skirt steak or sirloin also work. Freeze the steak for 20 to 30 minutes first to make thin slicing easier.
Avocado oil (2 tablespoons): Any high-heat oil works, such as peanut or light olive oil.
Soy sauce or tamari (1/4 cup): Use tamari or coconut aminos for gluten-free. Coconut aminos are sweeter, so cut back on the sweetener a bit.
Brown erythritol or monk fruit (2 tablespoons): Any brown sugar substitute works. Regular brown sugar works too if you are not eating keto.
Garlic and fresh ginger: Use 1/4 teaspoon ground ginger if you do not have fresh.
Xanthan gum (1/4 teaspoon, optional): Thickens the sauce with almost no carbs.
Baking soda (1 teaspoon, optional): For velveting the beef.
Green onions and sesame seeds: For garnish.

How to Make It at a Glance

Slice the steak thin against the grain. If you like, toss it with baking soda for 15 minutes, then rinse and pat dry.
Sear the steak in hot oil in batches, 1 to 2 minutes per side, then set it aside.
Lower the heat and cook the garlic and ginger in the rest of the oil for 30 seconds.
Add the soy sauce and sweetener and simmer 2 to 3 minutes. Stir in the xanthan gum if using.
Return the steak, toss for 1 to 2 minutes, and top with green onions and sesame seeds.

Common Mistakes to Avoid

Slicing with the grain. This makes the beef chewy. Look for the lines in the meat and cut across them.
Crowding the pan. Too many slices at once will steam and turn gray. Sear in batches.
Skipping the rinse. If you use baking soda, rinse it off well or the beef will taste soapy.
Too much xanthan gum. A little goes a long way. More than 1/4 teaspoon can make the sauce slimy. Sprinkle it in slowly while stirring.

Variations

Add vegetables: Stir-fry broccoli florets, sliced bell pepper, or snap peas after the steak and before the sauce.
Spicy: Add red pepper flakes or a drizzle of chili oil to the sauce.
Nutty flavor: Finish with a teaspoon of toasted sesame oil.
Chicken version: Use thinly sliced chicken thighs and cook until they reach 165°F.

What to Serve With It

Steamed broccoli is the classic keto pairing, since it soaks up the sauce. Cauliflower rice, shirataki noodles, or zucchini noodles also work well. A quick cucumber salad with rice vinegar adds a cool, crunchy side. If others at the table are not eating low carb, serve their portion over jasmine rice.

Storage and Reheating

Store leftovers in a covered container in the fridge for up to 3 days. Reheat in a hot skillet for 1 to 2 minutes, just until warm, or microwave in short bursts. Long reheating will toughen the thin slices of beef. It also packs well for lunch with a side of cauliflower rice.

Keto Mongolian Beef FAQ

What is velveting?
It is a Chinese cooking method that tenderizes meat. A short soak in baking soda raises the pH on the surface of the beef so it stays soft and juicy when seared.

Can I skip the xanthan gum?
Yes. The sauce will be thinner but still full of flavor. Simmer it an extra minute to reduce.

Is soy sauce keto?
Yes, in small amounts. It has about 1 gram of carbs per tablespoon.

Tips for the Best Mongolian Beef

Get the pan very hot. Wait until the oil shimmers before adding the steak. A hot pan gives you a browned crust in under 2 minutes.
Prep everything first. Mince the garlic, grate the ginger, and measure the sauce before you start. The cooking goes too fast to stop and chop.
Dry the steak. Pat the slices with paper towels, especially after velveting, so they sear instead of steam.
Taste the sauce. Sweeteners vary in strength. Start with 1 1/2 tablespoons and add more if you want it sweeter.

Budget Tips

Flank steak can be pricey. Sirloin tip or top round often cost less and work well when sliced thin and velveted with baking soda. Buy fresh ginger in a small knob and keep the rest in the freezer, where it grates easily straight from frozen. Adding a bag of frozen stir-fry vegetables also stretches 1 pound of beef to feed more people.