Follow these step-by-step instructions to create a restaurant-worthy stir-fry in your own kitchen. Preparation is key in stir-frying, so make sure to have all your ingredients prepped and ready to go before you start cooking.

Step 1: Prepare the Beef

• Start by thinly slicing the beef sirloin against the grain. This is crucial for tenderness. If the beef is partially frozen, it will be easier to slice thinly.
• In a medium bowl, marinate the beef. Combine 1 tablespoon of soy sauce, 1 teaspoon of sesame oil, and 1 tablespoon of cornstarch. Mix well to coat the beef evenly. This marinade will tenderize the beef and help it brown beautifully during stir-frying.
• Let the beef marinate for at least 15 minutes, or up to 30 minutes in the refrigerator for enhanced flavor.

Step 2: Prepare the Vegetables

• While the beef is marinating, prepare all your vegetables. Wash and chop the broccoli into bite-sized florets.
• Slice the bell peppers into strips, discarding the seeds and membranes.
• Julienne or thinly slice the carrots.
• Trim the snap peas.
• Slice the onion into wedges or half-moons.
• Mince the garlic and ginger. Having all your vegetables prepped and ready will ensure a smooth and quick stir-frying process.

Step 3: Make the Stir-Fry Sauce

• In a small bowl, whisk together the stir-fry sauce ingredients. Combine the remaining soy sauce, oyster sauce, rice vinegar, remaining sesame oil, brown sugar, and water.
• Whisk until the brown sugar is dissolved and the sauce is well combined. Set aside.

Step 4: Stir-Fry the Beef

• Heat a large wok or skillet over high heat until it is very hot. Add 1 tablespoon of vegetable oil.
• Once the oil is shimmering hot, add the marinated beef to the wok in a single layer. Avoid overcrowding the pan, as this will steam the beef instead of searing it. Work in batches if necessary.
• Stir-fry the beef for 2-3 minutes, or until it is browned on all sides and cooked through. Remove the beef from the wok and set aside.

Step 5: Stir-Fry the Vegetables

• Add the remaining tablespoon of vegetable oil to the wok.
• Add the onion and stir-fry for 1-2 minutes, until softened and fragrant.
• Add the garlic and ginger to the wok and stir-fry for another 30 seconds, until fragrant. Be careful not to burn the garlic.
• Add the broccoli florets, bell pepper strips, and carrots to the wok. Stir-fry for 3-4 minutes, until the vegetables are crisp-tender.
• Add the snap peas to the wok and stir-fry for another 1-2 minutes, until they are bright green and slightly tender-crisp.

Step 6: Combine and Finish

• Return the cooked beef to the wok with the vegetables.
• Pour the prepared stir-fry sauce over the beef and vegetables.
• Stir-fry everything together for 1-2 minutes, until the sauce has thickened and coats the beef and vegetables evenly. The cornstarch in the sauce will help it to thicken quickly.
• Cook until the sauce has reached your desired consistency.

Step 7: Serve Immediately

• Remove the stir-fry from the heat and serve immediately over hot cooked rice, noodles, or quinoa.
• Garnish with sesame seeds, chopped green onions, and red pepper flakes (if using) for added flavor and visual appeal.