If you love bold, saucy stir-fries but are watching carbs, this Keto Mongolian Beef hits the spot. It’s glossy, slightly sweet, and loaded with tender slices of beef and crisp vegetables — all without the sugar spike. The sauce clings to each piece of meat, the red bell pepper adds a pop of color, and the spring onions finish it with bright, oniony crunch. Serve it over cauliflower rice or a bed of leafy greens for a satisfyingly low-carb meal that feels indulgent.

Why you’ll love this recipe

Fast to make: From prep to plate in about 25–30 minutes.
Minimal ingredients: Pantry-friendly seasonings create a complex flavor with little effort.
Texture contrast: Tender steak, crisp pepper, and soft-tipped spring onions combine beautifully.
Saucy and keto-friendly: Uses erythritol for sweetness and tamari for depth, keeping carbs low.

Ingredients

▢1lb flat iron steak or flank steak or sirloin, fat removed, 450g
▢salt and black pepper
▢2 tablespoon light olive oil or avocado oil, for frying
▢1 tablespoon fresh ginger minced
▢3 cloves garlic minced
▢¼ teaspoon red pepper flakes or chili flakes
▢⅓ cup tamari or medium soy sauce or coconut aminos, 80ml
▢¼ cup water 60ml
▢2 tablespoon brown erythritol or more, to taste
▢1 red bell pepper sliced (110g)
▢2 large spring onions finely sliced (50g)
▢½ teaspoon toasted sesame seeds
▢drizzle of toasted sesame oil optional

Notes on ingredients

Choose a well-marbled cut such as flat iron or flank for the best texture once sliced thinly. Removing visible fat helps keep the dish lean and focused on the beef’s meaty flavor. Tamari or coconut aminos are both excellent low-carb, savory liquids; taste and pick the one you prefer. Brown erythritol provides the caramel-like sweetness without carbs; if you want it slightly sweeter, add a touch more at the end.

Equipment

Sharp knife and cutting board
Heavy skillet or wok
Mixing bowl
Measuring cups and spoons
Tongs or spatula

Prep: Slicing and measuring

Trim any visible fat from the 1lb flat iron steak or your chosen cut. For the most tender pieces, slice the steak very thinly across the grain. Thin slices cook quickly and stay tender rather than chewy. Mince the ginger and garlic, thinly slice the red bell pepper, and finely slice the spring onions so they’re ready when the sauce is done.

Step-by-step instructions

Season the beef. Pat the 1lb flat iron steak or flank or sirloin slices dry with paper towels, then season lightly with salt and black pepper on both sides. Drying the meat helps it sear instead of steam.
Heat the oil. Place a heavy skillet or wok over medium-high heat and add 2 tablespoon light olive oil or avocado oil. Allow the oil to shimmer but not smoke.
Sear the beef. Working in a single layer (do not crowd the pan), add the sliced beef to the hot oil. Sear the slices quickly, about 1–2 minutes per side, until browned and just cooked through. Use tongs or a spatula to turn pieces for an even sear. Transfer cooked beef to a plate and keep warm. If needed, cook in batches, adding a touch more oil between batches.
Sauté the aromatics. Lower the heat to medium. In the same pan with any leftover browned bits, add 1 tablespoon fresh ginger minced and 3 cloves garlic minced. Sprinkle in ¼ teaspoon red pepper flakes or chili flakes. Sauté, stirring constantly, until fragrant — about 30 seconds to 1 minute — being careful not to burn the garlic.
Make the sauce. Pour in ⅓ cup tamari or medium soy sauce or coconut aminos (80ml) and ¼ cup water (60ml). Stir to deglaze the pan, scraping up browned bits from the bottom. Add 2 tablespoon brown erythritol and stir until dissolved and the liquid becomes slightly glossy.
Add the pepper and return the beef. Add the sliced 1 red bell pepper (110g) to the pan and cook for 1–2 minutes until it begins to soften but remains crisp. Return the seared beef to the skillet, along with any juices that collected on the plate. Toss the meat and pepper in the sauce so each piece is coated and warmed through.
Finish with spring onions and sesame. Remove the pan from heat and stir in 2 large spring onions finely sliced (50g). Sprinkle ½ teaspoon toasted sesame seeds over the dish and drizzle a small amount of toasted sesame oil if using, to taste.
Adjust seasoning and sweetener. Taste the sauce and add more brown erythritol if you prefer a sweeter profile. If it tastes too salty, add a splash more water to balance. Once it’s balanced to your liking, transfer the beef to a serving plate.
Serve immediately. Serve the Keto Mongolian Beef over cauliflower rice, shredded cabbage, or a bed of mixed greens for a low-carb meal. Garnish additional sliced spring onions or sesame seeds if desired.

Timing and tips

Prep time: 10 minutes. Cook time: 15–20 minutes. Total time: 25–30 minutes.
Slice the steak thinly and against the grain for the most tender bite.
Do not crowd the pan when searing; crowding lowers the pan temperature and prevents a good sear.
Adjust the amount of erythritol to taste. Start with 2 tablespoon and add more if you prefer a sweeter glaze.
If you like more heat, add extra red pepper flakes or a splash of chili oil at the end.

Serving suggestions

This Keto Mongolian Beef is versatile. Here are a few ideas to round out the meal while keeping carbs low:

Cauliflower rice cooked in a little sesame oil and garlic for a classic pairing.
Sautéed or steamed broccoli for extra green veg and fiber.
Thinly sliced cucumber ribbons or a simple crisp salad to add freshness.
For meal prep, portion into containers and refrigerate for up to 3 days. Reheat gently on the stovetop or in a microwave, stirring midway.

Flavor variations

Small swaps let you customize the dish:

Swap tamari for coconut aminos for a slightly sweeter, lighter sauce.
Add a handful of sliced mushrooms with the red bell pepper for an earthier profile.
Stir in a teaspoon of rice vinegar or a squeeze of lime at the end for a bright, acidic lift.
For a thicker glaze, simmer the sauce a little longer before returning the beef, or whisk a small slurry of water and a pinch of xanthan gum and stir in at the end until thickened.

Nutrition snapshot (approximate per serving)

Estimated values will vary by exact ingredients and portion size, but this recipe emphasizes protein and healthy fats, with minimal carbs thanks to erythritol and low-carb sauces. Pairing with cauliflower rice keeps the meal keto-friendly while staying satisfying and nutrient-rich.

Troubleshooting

If the beef is tough: Make sure you sliced against the grain and cooked it only until just done; overcooking lean slices makes them chewy.
If the sauce won’t thicken: Simmer slightly longer to reduce, or add a very small xanthan gum slurry to achieve a glossy finish.
If the taste is too salty: Add a splash more water and a touch more erythritol to rebalance.

Final thoughts

This version of Keto Mongolian Beef captures the sticky, savory-sweet essence of the classic while staying low-carb and simple. It’s a weeknight dinner winner — quick, flavorful, and adaptable. Whether you serve it over cauliflower rice, crisp greens, or enjoy it as a protein-forward main, the glossy sauce and tender slices of steak make every bite worth it.

Ready to cook? Gather the 1lb flat iron steak or your chosen cut, the tamari, and a few pantry staples, and you’ll have a restaurant-worthy stir-fry on the table in under half an hour. Enjoy the contrast of tender meat, crunchy pepper, and bright spring onions in this satisfying Keto Mongolian Beef.

Keto Mongolian Beef

A quick, flavorful keto-friendly Mongolian beef stir-fry with a savory-sweet tamari sauce.

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Prep Time 5

Cook Time 15

Total Time 20

Servings: 3 servings

Ingredients Equipment Method Notes

Ingredients

1 lb flat iron steak (or flank steak or sirloin), fat removed about 450 g
salt to season
black pepper to season
2 tablespoons light olive oil or avocado oil for frying
1 tablespoon fresh ginger minced
3 cloves garlic minced
1/4 teaspoon red pepper flakes or chili flakes
1/3 cup tamari or medium soy sauce or coconut aminos, about 80 ml
1/4 cup water about 60 ml
2 tablespoons brown erythritol or more to taste
1 red bell pepper sliced (about 110 g)
2 large spring onions finely sliced (about 50 g)
1/2 teaspoon toasted sesame seeds
toasted sesame oil optional, drizzle to finish

Equipment

large wok or large frying pan
Sharp Knife
Cutting Board
Measuring Spoons
Measuring Cups

Method

Freeze the steak for about 20 minutes to firm it, then slice against the grain into ½ cm (thin) slices; season the strips with salt and black pepper.
Heat 2 tablespoons oil in a large wok or frying pan over high heat until very hot to ensure a good sear.
Working in one or two batches to avoid crowding, fry the beef undisturbed for 4 minutes, then turn and cook 1–2 more minutes until just cooked through; transfer to a plate and set aside.
In the same pan, add the minced ginger, garlic and red pepper flakes and sauté for about 1 minute until fragrant.
Add the tamari (or soy sauce/coconut aminos), brown erythritol and water; turn the heat up to bring to a boil, then reduce to medium and simmer 3–4 minutes until the sauce reduces and thickens slightly.
Return the cooked beef to the pan along with the sliced red bell pepper and cook 2–3 minutes more until peppers are just tender but still crisp.
Turn off the heat, stir in the sliced spring onions, sprinkle with toasted sesame seeds and drizzle with toasted sesame oil if using; season with extra black pepper to taste and serve.

Notes

Net carbs are about 5.3 g per serve (recipe makes 3 portions).
Freeze the beef for 20 minutes before slicing to make thin slices more easily.
For a stickier sauce, thicken with 1/4 tsp xanthan gum, 1 tsp ground chia, or 1 tsp beef collagen after reducing.
Store leftovers in the fridge for up to 3 days or freeze for up to 3 months.