Keto Beef Pepper Steak

Keto Beef Pepper Steak is tender, savory, and bursting with colorful bell peppers in a rich, umami-packed sauce, all without the carbs! This is the kind of dinner that makes you forget you’re even eating keto. It’s quick, it’s satisfying, and honestly? It tastes like takeout but WAY better because you made it yourself. My family requests this at least twice a month, and I never get tired of it!

Why You’ll Love This Recipe

This Keto Beef Pepper Steak is a total game-changer. First off, it comes together in under 30 minutes, which is perfect for those crazy weeknights when you need something fast but don’t want to sacrifice flavor.

The beef is melt-in-your-mouth tender, the peppers stay crisp and vibrant, and that sauce? Oh honey, that sauce is everything. It’s savory, slightly tangy, with just a hint of heat if you want it.

Plus, it’s completely keto-friendly with NO cornstarch or sugar—just real, wholesome ingredients that keep you in ketosis while making your taste buds do a happy dance.

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Ingredient List

Beef & Marinade

• 1 lb (450 g) flank steak or sirloin, thinly sliced against the grain
• 2 tablespoons soy sauce or coconut aminos (for keto)
• 1 teaspoon sesame oil
• 1 teaspoon minced garlic
• ½ teaspoon ground black pepper

Stir-Fry

• 2 tablespoons olive oil or avocado oil
• 1 medium green bell pepper, thinly sliced
• 1 medium red bell pepper, thinly sliced
• 1 medium yellow or orange bell pepper, thinly sliced
• 1 small onion, thinly sliced
• 2–3 cloves garlic, minced
• 1 inch fresh ginger, minced (optional but great)

Sauce (Keto-Friendly)

• ¼ cup beef broth or water
• 2 tablespoons soy sauce or coconut aminos
• 1 tablespoon rice vinegar or apple cider vinegar
• 1–2 teaspoons chili garlic sauce or hot sauce (optional heat)
• ½–1 teaspoon low-carb sweetener (like erythritol or monk fruit, optional)

Thickener (Keto Friendly)

• 1 teaspoon xanthan gum (sprinkle to thicken)

Garnish

• Sesame seeds
• Sliced green onions

Friendly Notes: If you can’t find flank steak, ribeye or strip steak works beautifully too—just slice it thin! Coconut aminos are my go-to for a slightly sweeter, soy-free option. And don’t skip the ginger if you have it; it adds such a lovely warmth to the dish!

Why These Ingredients Work

Let me break down the magic happening in this recipe! The flank steak is perfect because it’s lean, flavorful, and when sliced against the grain, it becomes incredibly tender. The marinade does double duty—it flavors the meat AND helps tenderize it with those enzymes in the soy sauce and garlic.

Those gorgeous bell peppers aren’t just pretty—they add natural sweetness and a satisfying crunch that balances the rich beef. Plus, they’re low-carb superstars! The sesame oil brings that authentic Asian restaurant flavor, while the garlic and ginger create an aromatic base that makes your whole kitchen smell amazing.

Now here’s the keto secret weapon: xanthan gum. This is what thickens our sauce without any cornstarch or flour. Just a tiny bit goes a long way, and it keeps this dish completely low-carb while giving you that luscious, glossy sauce that clings to every piece of beef and pepper. The coconut aminos or soy sauce delivers that umami punch, and the vinegar cuts through the richness with just the right amount of tang. It’s all about balance, friends!

Essential Tools and Equipment

You don’t need anything fancy for this recipe—just your basic kitchen essentials:

• Large skillet or wok (at least 12 inches is ideal for proper stir-frying)
• Sharp knife for slicing beef and veggies thin
• Cutting board
• Two medium mixing bowls (one for marinade, one for sauce)
• Whisk for combining sauce ingredients
• Tongs or wooden spoon for stir-frying
• Measuring spoons and cups

Inez’s Tip: A wok is fantastic if you have one because the high sides make tossing everything so much easier, but honestly? A good heavy-bottomed skillet works just as well!

How To Make Keto Beef Pepper Steak

Step 1: Marinate the Beef

In a medium bowl, combine your sliced beef with the soy sauce (or coconut aminos), sesame oil, minced garlic, and black pepper. Use your hands to really massage that marinade into every piece of meat—don’t be shy! Let it sit for 10–20 minutes while you prep your veggies.

Step 2: Prep the Sauce

In a small bowl, whisk together the beef broth (or water), soy sauce or coconut aminos, vinegar, chili garlic sauce if you’re using it, and your low-carb sweetener. Give it a good whisk until everything’s combined. Set this aside—you’ll pour it in later, and having it ready to go makes the cooking process so much smoother.

Step 3: Stir-Fry the Beef

Heat 1 tablespoon of oil in your large skillet or wok over medium-high heat. Once it’s shimmering (but not smoking), add your marinated beef in a single layer. This is important—don’t crowd the pan! Let it sear for 2–3 minutes on one side without moving it.

Step 4: Cook the Veggies

Add the remaining tablespoon of oil to the same pan (don’t wipe it out—all those browned bits add flavor!). Toss in your sliced bell peppers and onion. Stir-fry for 3–5 minutes, keeping everything moving. You want the peppers to be crisp-tender—still bright and with a little snap to them. In the last 30–60 seconds, add your minced garlic and ginger.

Step 5: Combine & Sauce

Now bring that beautiful beef back to the party! Return it to the pan with all those gorgeous peppers. Pour in your prepared sauce and give everything a good stir. Let it all cook together for 2–3 minutes so the flavors can mingle and get to know each other.

Step 6: Thicken With Xanthan Gum (Keto Secret!)

Here’s the trick to getting that perfect restaurant-style glossy sauce without any cornstarch: sprinkle your xanthan gum EVENLY over the mixture while stirring constantly. Keep stirring for about 1 minute, and you’ll watch the sauce transform right before your eyes. It’ll thicken up beautifully and coat everything in that luscious glaze.

Step 7: Finish & Serve

Remove your skillet from the heat. Sprinkle with sesame seeds and sliced green onions, and you’re done! Seriously, that’s it. From start to finish, you’ve just created a restaurant-quality keto meal in your own kitchen.

You Must Know

Let me share some insider secrets that’ll take your Keto Beef Pepper Steak from good to OUTSTANDING:

Slice Against the Grain: This is THE most important tip for tender beef. Look at your meat and find the direction the muscle fibers are running. Then slice perpendicular to those lines. This shortens the fibers and makes every bite melt-in-your-mouth tender. I can’t stress this enough!

High Heat is Your Friend: Stir-frying needs high heat to get that beautiful caramelization. If your heat is too low, everything will steam and you’ll lose that amazing flavor development.

Don’t Skip the Sear: When you add the beef to the hot pan, resist the urge to move it around immediately. Let it sit for those first 2-3 minutes to develop a gorgeous brown crust. That’s where so much flavor lives!

Pro Tips & Cooking Hacks

Prep Everything First: Stir-frying happens FAST. Have all your ingredients prepped, measured, and within arm’s reach before you turn on the stove. This is what chefs call “mise en place,” and it’ll make your cooking experience so much smoother and less stressful.

Use the Right Oil: Avocado oil is my absolute favorite for high-heat cooking because it has a high smoke point and a neutral flavor. Olive oil works too, but avoid extra virgin—save that for drizzling. Regular olive oil or light olive oil is better for cooking at high temps.

Batch Cooking Tip: Double this recipe and use the leftovers for meal prep! It reheats beautifully and tastes even better the next day after the flavors have had time to develop.

Make It Spicier: Love heat? Add a pinch of red pepper flakes along with the garlic, or drizzle some sugar-free Sriracha over the finished dish. My husband likes to add fresh sliced jalapeños with the peppers!

Common Mistakes to Avoid:

• Clumpy Xanthan Gum: Always sprinkle while stirring. Never dump it in one spot!
• Overcrowded Pan: This makes everything steam instead of sear. Cook in batches if needed.
• Mushy Peppers: Don’t overcook them! They should stay bright and crisp-tender, not soft and dull.

Flavor Variations & Suggestions

This recipe is so versatile! Here are some fun ways to switch it up:

Protein Swaps: Use chicken breast, pork tenderloin, or even shrimp instead of beef. Just adjust cooking times accordingly—shrimp only needs 2-3 minutes total!

Veggie Additions: Throw in some mushrooms, snap peas, or broccoli florets. Zucchini ribbons are also amazing and keep it keto-friendly!

Asian-Inspired Twist: Add a tablespoon of unsweetened peanut butter or almond butter to the sauce for a Thai-style flavor. So good!

Mediterranean Variation: Skip the Asian seasonings and use Italian herbs, olives, and a squeeze of lemon instead. Totally different vibe, totally delicious.

Extra Umami Bomb: Add a splash of fish sauce to the sauce mixture. It sounds weird, but trust me—it adds incredible depth without tasting fishy at all.

Make-Ahead Options

This is where Keto Beef Pepper Steak really shines for busy weeks:

Meal Prep Magic: Make the full recipe on Sunday and portion it into individual containers. It’ll stay fresh in the fridge for 4–5 days. Just reheat in the microwave or in a skillet with a splash of water or broth.

Marinate in Advance: Slice and marinate your beef up to 24 hours ahead. Keep it covered in the fridge, and it’ll be even more flavorful and tender when you’re ready to cook.

Prep the Veggies: Slice all your peppers and onions up to 2 days ahead. Store them in an airtight container or zip-top bag in the fridge.

Freeze the Beef: You can actually freeze the marinated beef in a freezer bag for up to 3 months. Just thaw it in the fridge overnight before cooking. I don’t recommend freezing the finished dish because the peppers can get a bit mushy, but the raw marinated beef freezes beautifully!

Recipe Notes & Baker’s Tips

About Xanthan Gum: If you don’t have xanthan gum, you can skip the thickening step entirely. The sauce will be thinner, more like a stir-fry glaze, but it’ll still taste incredible. You could also use a tiny bit (½ teaspoon) of glucomannan powder, which works similarly.

Soy Sauce vs. Coconut Aminos: Both work great! Soy sauce is more traditional and has a stronger, saltier flavor. Coconut aminos are naturally gluten-free, slightly sweeter, and have less sodium. I use coconut aminos most of the time because I love that subtle sweetness.

Meat Selection: Flank steak is my first choice because it’s affordable and flavorful, but sirloin is excellent too. Even ribeye or New York strip work wonderfully if you’re feeling fancy! Just make sure to trim excess fat if you’re using a fattier cut.

Ginger is Optional BUT… I strongly encourage you to use it! Fresh ginger adds such a bright, warm note that really elevates the dish. If you don’t have fresh, you can use ¼ teaspoon ground ginger, but fresh is always best.

Serving Suggestions

This Keto Beef Pepper Steak is pretty complete on its own, but here are some fantastic ways to serve it:

Cauliflower Rice: This is my go-to! It soaks up all that delicious sauce and keeps everything low-carb. You can make your own or grab a bag of frozen cauliflower rice for ultimate convenience.

Shirataki Noodles: Also called “miracle noodles,” these are virtually carb-free and have a great texture when prepared properly. Rinse them well and dry-fry them in a pan before adding to remove any excess moisture.

Zucchini Noodles (Zoodles): Quick, fresh, and light. Just don’t overcook them or they’ll get watery!

Over Greens: Serve it over a big bed of baby spinach or mixed greens for a deconstructed stir-fry salad situation. The warm beef and peppers will slightly wilt the greens—it’s amazing!

Keto Wraps: Spoon it into low-carb tortillas with some shredded lettuce and a dollop of sour cream. Instant keto fajitas!

Lettuce Cups: For a fun, hands-on meal, serve it in crisp butter lettuce or romaine leaves. Perfect for a lighter dinner!

Optional Garnishes: Beyond the sesame seeds and green onions, try fresh cilantro, a lime wedge for squeezing, or a sprinkle of everything bagel seasoning for a fun twist!

How to Store Your Keto Beef Pepper Steak

Refrigerator Storage: Store leftovers in an airtight container in the fridge for up to 4–5 days. Make sure it’s completely cooled before sealing the container to prevent condensation.

Freezer Storage: I don’t recommend freezing the cooked dish because the peppers and onions lose their texture and become mushy when thawed. However, you CAN freeze the marinated raw beef (as I mentioned earlier) for up to 3 months.

Reheating Instructions:

• Microwave: Transfer to a microwave-safe dish, cover loosely, and heat in 1-minute intervals, stirring between each, until heated through. Add a tiny splash of water or broth if it seems dry.
• Stovetop: This is my preferred method! Heat a skillet over medium heat, add your leftovers with a tablespoon of water or broth, and stir frequently until warmed through. Takes about 5 minutes and keeps everything from drying out.
• Air Fryer: You can reheat it at 350°F for 5-7 minutes, but be aware the peppers will get a bit softer.

Pro Tip: Store the sesame seeds and green onions separately and add them fresh when you reheat. It makes such a difference in presentation and texture!

Allergy Information

Let’s talk about potential allergens and how to work around them:

Common Allergens in This Recipe:

• Soy (in soy sauce and some sesame oils)
• Sesame (sesame oil and sesame seeds)
• Sulfites (sometimes in beef broth)

Allergy-Friendly Substitutions:

Soy Allergy: Use coconut aminos instead of soy sauce—it’s completely soy-free and tastes very similar! For sesame oil, you can substitute with a bit of toasted almond oil or just use more avocado oil and add a pinch of toasted sesame seeds at the end for that nutty flavor.

Sesame Allergy: Skip the sesame oil and seeds entirely. Use avocado oil for cooking and garnish with chopped nuts (almonds or cashews) instead of sesame seeds for that crunch factor.

Gluten-Free: Make sure you use gluten-free soy sauce (tamari) or coconut aminos. Regular soy sauce contains wheat!

Nightshade Sensitivity: If you can’t have peppers, try using zucchini, yellow squash, or mushrooms instead. You’ll lose some of that vibrant color, but the dish will still be delicious!

Garlic/Onion Sensitivity: You can use garlic-infused oil (the oil is safe on low-FODMAP diets) and skip the raw garlic and onions. Add extra ginger for flavor instead.

Questions I Get Asked A Lot

Can I use a different cut of beef?

Absolutely! While flank steak is my favorite for this recipe, you can use sirloin, ribeye, strip steak, or even skirt steak. The key is to slice it thinly against the grain no matter which cut you choose. Avoid tougher cuts like chuck roast unless you’re planning to cook it low and slow—those need more time to become tender.

My sauce didn’t thicken—what happened?

This usually happens if the xanthan gum clumped instead of dispersing evenly. Make sure you’re sprinkling it like you’re salting something, not dumping it in one spot. Also, give it a full minute of stirring and cooking time—it needs heat to activate properly. If your sauce is still too thin, you can sprinkle just a tiny pinch more, but be conservative!

Can I make this without xanthan gum?

Yes! The xanthan gum just gives you that thick, glossy sauce that clings to everything. Without it, you’ll have a thinner, more broth-like sauce—which is still totally delicious, just a different texture. Some people actually prefer it that way! You could also reduce the sauce a bit longer to naturally thicken it through evaporation.

How do I know if I’m slicing against the grain?

Look closely at your raw beef. You’ll see lines running through it—those are the muscle fibers or “grain.” You want to cut perpendicular (at a 90-degree angle) to those lines. So if the lines run left to right, you cut up and down. This shortens the muscle fibers and makes the meat much more tender. If you slice WITH the grain, you’ll have chewy, stringy beef.

Can I add more vegetables?

Of course! This recipe is super flexible. Broccoli florets, snap peas, mushrooms, bok choy, or zucchini would all be fantastic additions. Just keep in mind that different vegetables have different cooking times. Add harder vegetables (like broccoli) with the peppers, and softer ones (like zucchini or mushrooms) toward the end.

Is this recipe spicy?

Not as written—it’s savory and a bit tangy but not spicy. The black pepper gives it a mild kick, but nothing intense. If you want heat, add the chili garlic sauce or hot sauce to the sauce mixture, or sprinkle red pepper flakes when you add the garlic. Start with a little and taste as you go—you can always add more heat, but you can’t take it away!

Why do I need to cook the beef separately from the vegetables?

Great question! Cooking them separately ensures that the beef gets a proper sear and stays tender, while the vegetables retain their bright color and crisp texture. If you cook everything together, the moisture from the vegetables will make the beef steam instead of brown, and you’ll end up with gray meat and mushy peppers. The extra few minutes is totally worth it!

💬 Tried this recipe? Leave a comment and rating below! I absolutely LOVE hearing from you! Tell me—did you add extra heat? Try a different veggie combination? Let me know in the comments!