Of all the recipes in my weeknight dinner rotation, this Beef Stir Fry with Bell Peppers holds a special place. I remember the first time I made it, I was in a frantic rush, staring at a pack of flank steak and a colorful trio of bell peppers, wondering how to turn them into something a family of notoriously picky eaters would actually enjoy. The kitchen soon filled with the most incredible aroma—the savory sizzle of beef hitting a hot wok, the sharp scent of garlic and ginger, and the sweet perfume of caramelizing onions and peppers. When I brought the steaming platter to the table, the vibrant colors alone were enough to silence the usual dinner-time complaints. My husband took one bite and his eyes widened. My youngest, who typically inspects every piece of food with suspicion, happily crunched on a red pepper strip coated in the glossy, savory-sweet sauce. It was a certified hit. Now, it’s our go-to meal for a reason: it’s incredibly fast, endlessly customizable, and delivers that satisfying, restaurant-quality flavor right at home. It’s more than just a recipe; it’s our delicious solution to the “what’s for dinner?” dilemma.

Ingredients

Here is everything you will need to create this vibrant and flavorful dish. The ingredients are separated into three components—the beef and its marinade, the all-important stir-fry sauce, and the fresh vegetables and aromatics—to make preparation seamless.

For the Beef and Marinade:

• 1.5 lbs Flank Steak (or Sirloin/Skirt Steak): Sliced very thinly against the grain for maximum tenderness.
• 1 tablespoon Soy Sauce (or Tamari): Provides the initial savory, umami flavor base for the beef.
• 1 tablespoon Cornstarch: The secret ingredient for “velveting” the beef, creating a tender texture and a light coating that helps the sauce cling to it.
• 1 teaspoon Sesame Oil: Adds a nutty, aromatic depth to the marinade.
• 1/2 teaspoon Black Pepper: For a touch of gentle spice.

For the Savory Stir-Fry Sauce:

• 1/2 cup Low-Sodium Beef Broth: Forms the liquid base of our sauce, adding a rich, meaty flavor without excessive salt.
• 1/4 cup Low-Sodium Soy Sauce (or Tamari for gluten-free): The primary source of savory, salty, and umami flavor in the sauce. Using low-sodium gives you control over the final saltiness.
• 2 tablespoons Oyster Sauce: A thick, rich sauce that provides a unique savory-sweetness and glossy sheen. Do not skip this for authentic flavor.
• 1 tablespoon Rice Vinegar: Adds a bright, acidic note that cuts through the richness and balances the flavors.
• 1 tablespoon Brown Sugar (or Honey/Maple Syrup): Provides a touch of sweetness to balance the salty and sour elements, helping the sauce caramelize slightly.
• 1 tablespoon Sesame Oil: Reinforces the nutty aroma and adds a silky finish to the sauce.
• 1 tablespoon Cornstarch: This will act as the thickening agent, transforming the liquid into a luscious, glossy sauce that coats every ingredient.

For the Stir-Fry:

• 2 tablespoons High-Smoke-Point Oil (e.g., Avocado, Canola, or Peanut Oil): Essential for stir-frying at high temperatures without burning.
• 1 large Yellow Onion: Sliced into thin wedges to provide a sweet, aromatic foundation.
• 3 Bell Peppers (a mix of red, yellow, and green): Seeded and sliced into thin, uniform strips for vibrant color, sweetness, and a crisp-tender texture.
• 4 cloves Garlic: Minced finely, delivering a pungent, aromatic kick that is fundamental to stir-fry flavor.
• 1 tablespoon Ginger: Freshly grated or minced, it adds a warm, zesty spice that complements the beef perfectly.
• Optional Garnishes: Toasted sesame seeds, sliced green onions, or fresh cilantro for a final flourish of flavor and texture.

Instructions

Follow these step-by-step instructions for a perfect stir-fry every time. The key to a great stir-fry is preparation—having everything chopped, measured, and ready to go before you even turn on the heat. This process is called mise en place, and it’s non-negotiable for a fast-cooking dish like this one.

Step 1: Prepare and Marinate the Beef

First, prepare your beef. If your steak is not yet sliced, it’s helpful to place it in the freezer for 15-20 minutes. This firms up the meat, making it significantly easier to slice thinly and uniformly. Identify the direction of the muscle fibers (the grain) running through the steak. Using a sharp knife, slice the beef very thinly (about 1/8-inch thick) against the grain. Slicing against the grain severs the long, tough muscle fibers, resulting in incredibly tender bites of beef.

In a medium bowl, combine the sliced beef with 1 tablespoon of soy sauce, 1 tablespoon of cornstarch, 1 teaspoon of sesame oil, and the black pepper. Use your hands or a spoon to toss the beef thoroughly, ensuring every slice is evenly coated in the marinade. The cornstarch is crucial here; it creates a protective layer that keeps the beef moist and tender during the high-heat cooking process. Set the bowl aside to marinate for at least 15 minutes, but for more flavor, you can let it sit for up to 30 minutes at room temperature.

Step 2: Prepare the Vegetables and Sauce

While the beef is marinating, it’s time to get all your other components ready. Wash and prepare your vegetables. Slice the onion into thin wedges. Core and seed the bell peppers, then slice them into strips of a similar thickness to your onion wedges. Uniformity in size helps everything cook evenly. Mince your garlic cloves and grate the fresh ginger. Keep the garlic and ginger together in a small bowl, as they will be added to the pan at the same time.

In a separate small bowl or a liquid measuring cup, prepare the stir-fry sauce. Whisk together the beef broth, low-sodium soy sauce, oyster sauce, rice vinegar, brown sugar, sesame oil, and the remaining 1 tablespoon of cornstarch. Continue whisking until the cornstarch and sugar are fully dissolved and there are no lumps. This step is vital—if the cornstarch isn’t fully dissolved, your sauce will be lumpy. Set the sauce mixture near your stove.

Step 3: Sear the Beef

Place a large wok or a heavy-bottomed skillet (cast iron works great) over high heat. Let the pan get screaming hot. You should see faint wisps of smoke coming off the surface. Add 1 tablespoon of your high-smoke-point oil. Swirl to coat the bottom of the pan.

Carefully add half of the marinated beef to the hot pan in a single layer. Do not overcrowd the pan. Overcrowding will cause the beef to steam rather than sear, resulting in grey, tough meat. Let the beef cook undisturbed for 60-90 seconds per side, until it develops a deep brown crust. Use tongs to flip and sear the other side. Once seared, remove the beef from the pan and place it on a clean plate. Add the remaining 1 tablespoon of oil to the pan, let it get hot again, and repeat the process with the second batch of beef. Set all the seared beef aside.

Step 4: Cook the Aromatics and Vegetables

Reduce the heat slightly to medium-high. To the same pan, add the sliced yellow onion and bell peppers. Stir-fry for 3-4 minutes, tossing frequently. You want the vegetables to become crisp-tender—they should be slightly softened but still have a bit of a bite and vibrant color. If the pan seems dry, you can add a splash of the beef broth or a teaspoon of oil.

Once the peppers and onions are nearly done, push them to the sides of the pan to create a well in the center. Add the minced garlic and grated ginger to this well. Cook for about 30-45 seconds, stirring constantly, until they become fragrant. Be careful not to burn the garlic, as it will turn bitter. Once fragrant, mix the garlic and ginger in with the rest of the vegetables.

Step 5: Combine and Finish the Stir-Fry

Return the seared beef and any accumulated juices from the plate back into the wok with the vegetables. Give the prepared stir-fry sauce another quick whisk to ensure the cornstarch hasn’t settled at the bottom. Pour the sauce all over the beef and vegetables.

Continue to cook, stirring constantly, for 1-2 minutes. The heat will activate the cornstarch in the sauce, causing it to bubble and thicken into a beautiful, glossy glaze that coats every single ingredient. Once the sauce has thickened and is clinging to the beef and peppers, remove the pan from the heat immediately to prevent overcooking.

Step 6: Serve Immediately

Transfer the Beef and Pepper Stir-Fry to a large serving platter. Garnish generously with toasted sesame seeds and thinly sliced green onions if desired. Serve hot and enjoy the fruits of your labor!

Nutrition Facts

• Servings: 4-6 servings
• Calories per Serving: Approximately 380-450 kcal (This can vary based on the specific cut of beef and oil used.)

1. High in Protein: A single serving provides a substantial amount of high-quality protein from the beef, which is essential for muscle repair, growth, and overall body function.
2. Rich in Iron: Beef is an excellent source of heme iron, a form of iron that is more easily absorbed by the body than the iron from plant sources. Iron is crucial for creating red blood cells and preventing fatigue.
3. Excellent Source of Vitamin C: The bell peppers, especially the red and yellow varieties, are packed with Vitamin C, a powerful antioxidant that supports the immune system and helps the body absorb iron.
4. Source of B Vitamins: This dish provides important B vitamins like B12 and B6 from the beef, which are vital for energy metabolism and neurological health.
5. Controllable Sodium: By using low-sodium soy sauce and beef broth, you have greater control over the total sodium content, making this a healthier alternative to many takeout options.

Preparation Time

This recipe is a champion of weeknight efficiency, but the total time depends heavily on your knife skills.

• Prep Time: 20-25 minutes. This includes slicing the steak, chopping all the vegetables, mincing the aromatics, and mixing the marinade and sauce. Taking your time here makes the cooking process smooth and stress-free.
• Cook Time: 10-12 minutes. The actual stir-frying process is incredibly fast. From the moment the beef hits the pan to the final thickening of the sauce, it’s a quick-fire culinary adventure.
• Total Time: Approximately 30-35 minutes.

How to Serve

This Beef Stir Fry with Bell Peppers is a versatile centerpiece that can be served in numerous delightful ways. Here are some popular and creative serving suggestions:

• Classic Rice Bowl:
  • Serve a generous scoop of the stir-fry over a bed of fluffy steamed jasmine rice. The neutral, fragrant rice is the perfect vessel for soaking up every last drop of the savory sauce.
  • For a healthier, nuttier alternative, use brown rice or quinoa.
• Noodle Night:
  • Toss the finished stir-fry with cooked lo mein noodles or udon noodles directly in the wok for a complete, one-pan noodle dish.
  • Serve it alongside crispy chow mein noodles for a textural contrast.
• Low-Carb Options:
  • For a keto-friendly or low-carb meal, serve the stir-fry over a bed of cauliflower rice or zucchini noodles (zoodles).
  • Enjoy it on its own, perhaps with a side of steamed green beans or edamame.
• Lettuce Wraps:
  • Spoon the beef and pepper mixture into crisp, cool leaves of iceberg or butter lettuce for a fun, interactive, and light meal.
• Finishing Touches and Garnishes:
  • Texture and Flavor: Sprinkle with toasted sesame seeds and thinly sliced green onions.
  • Freshness: Add a handful of fresh cilantro leaves right before serving.
  • A Kick of Heat: Offer a side of sriracha, chili garlic sauce, or red pepper flakes for those who like it spicy.

Additional Tips

Master the art of stir-frying with these eight essential tips that will elevate your dish from good to unforgettable.

1. The Secret to Tender Beef is Twofold: Don’t just slice the beef thinly; you must slice it against the grain. This physically shortens the muscle fibers, making them tender. The second part of the secret is the cornstarch in the marinade. This technique, known as “velveting,” creates a silky coating that protects the beef from the intense heat, locking in moisture.
2. High Heat is Your Best Friend: The soul of a great stir-fry is the “wok hei,” a distinct, smoky flavor achieved only with very high heat. Get your wok or skillet as hot as possible before adding the oil. This ensures the ingredients sear rather than steam, giving you perfectly browned meat and crisp vegetables.
3. Don’t Crowd the Pan: This is the most common mistake in stir-frying. Adding too much food to the pan at once dramatically lowers the temperature, leading to steamed, grey beef and soggy vegetables. Cook the beef in two or even three small batches to ensure each piece has direct contact with the hot surface and develops a beautiful crust.
4. Embrace the Mise en Place: As mentioned in the instructions, this French term for “everything in its place” is the golden rule of stir-frying. The cooking process is too fast to pause for chopping. Have every single ingredient—sliced beef, chopped veggies, minced aromatics, and pre-mixed sauce—ready and within arm’s reach before you start cooking.
5. Vegetable Order Matters: Not all vegetables cook at the same rate. Add harder, denser vegetables like bell peppers and onions first. Cook them for a few minutes before adding quicker-cooking ingredients. If you were adding broccoli florets, they would go in with the peppers. If you were adding snow peas or bok choy leaves, you’d add them in the last minute of cooking.
6. The Right Pan for the Job: A carbon steel wok is the traditional and ideal choice because its shape allows for easy tossing and concentrated heat at the bottom. However, a large, flat-bottomed cast-iron or stainless steel skillet is an excellent substitute. Avoid non-stick pans if possible, as most cannot handle the high heat required for a proper sear.
7. Customize Your Vegetables: This recipe is a fantastic template. Feel free to swap or add other vegetables based on what’s in your fridge. Broccoli florets, snow peas, sliced mushrooms, baby corn, water chestnuts, and asparagus are all wonderful additions. Just be mindful of their different cooking times.
8. Control Your Sauce Thickness: If your sauce seems too thin for your liking after adding it, let it bubble for another 30 seconds. If it’s still not thick enough, create a “slurry” by mixing 1 teaspoon of cornstarch with 2 teaspoons of cold water in a small bowl. Slowly drizzle this slurry into the simmering sauce while stirring, and it will thicken up almost instantly.

FAQ Section

Here are answers to some of the most frequently asked questions about making the perfect Beef Stir Fry with Bell Peppers.

1. What is the absolute best cut of beef for stir-fry?
Flank steak is widely considered the best choice due to its intense beefy flavor and lean texture that holds up well to high-heat cooking. Its long muscle fibers make it easy to identify the grain for proper slicing. Other excellent options include sirloin steak, skirt steak, and even flat iron steak. Avoid stewing meats like chuck roast, as they will be too tough.

2. My beef always comes out tough and chewy. What am I doing wrong?
This is usually caused by one of three things: slicing with the grain instead of against it, skipping the velveting/marinating step with cornstarch, or overcooking. Slicing against the grain is the most critical step for tenderness. Velveting protects the meat, and cooking it quickly in hot batches prevents it from becoming tough and rubbery.

3. Can I make this recipe ahead of time for meal prep?
Absolutely. You can prep all the components ahead of time and store them separately in the refrigerator: the marinated beef, the chopped vegetables, and the mixed sauce. When you’re ready to eat, the cooking process will take only 10-12 minutes. You can also cook the entire dish ahead, but be aware that the vegetables will lose some of their crispness upon reheating.

4. What’s the best way to store and reheat leftovers?
Store any leftovers in an airtight container in the refrigerator for up to 3-4 days. To reheat, it’s best to use a skillet or wok over medium heat. Add a splash of water or beef broth to help loosen the sauce and gently heat the stir-fry until warmed through. Microwaving works, but it can sometimes make the beef a bit tougher and the vegetables softer.

5. How can I make this recipe gluten-free?
It’s very simple to adapt this recipe for a gluten-free diet. Replace the regular soy sauce with certified gluten-free tamari or coconut aminos in both the marinade and the sauce. Also, ensure your oyster sauce and beef broth are labeled as gluten-free, as some brands can contain wheat.

6. My stir-fry came out watery and the sauce didn’t thicken. Why?
A watery stir-fry is almost always a result of too much moisture being released from the ingredients, which happens when the pan isn’t hot enough or is overcrowded. This steams the food instead of searing it. To fix a watery sauce on the fly, use the cornstarch slurry trick mentioned in the tips section (1 tsp cornstarch mixed with 2 tsp cold water) to thicken it up at the end.

7. Can I use frozen bell peppers or other frozen vegetables?
Yes, you can, but with a caveat. Frozen vegetables release a lot of water. Do not thaw them first. Add them directly from the freezer to the hot pan after the onions have cooked for a minute. You may need to cook them a bit longer to evaporate the excess moisture before proceeding with the recipe. They won’t be as crisp as fresh vegetables, but they are a convenient option.

8. I don’t own a wok. Can I still make a great stir-fry?
Yes! While a wok is ideal, you can make a fantastic stir-fry in any large, heavy-bottomed skillet. A 12-inch cast-iron skillet is a superb alternative because it retains heat incredibly well, which is crucial for getting a good sear. A heavy-duty stainless steel skillet also works. The key is to ensure the pan is large enough to avoid overcrowding and can handle high temperatures.

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