Follow these steps carefully for a perfect stir-fry every time. The key is to have all your ingredients prepped and ready to go before you even turn on the stove, a practice known as “mise en place.”

1. Marinate the Beef: In a medium bowl, combine the thinly sliced flank steak, 2 tablespoons of soy sauce, 1 tablespoon of cornstarch, 1 teaspoon of sesame oil, and black pepper. Toss everything together with your hands or tongs until the beef is evenly coated. The cornstarch will feel a bit sticky, which is exactly what you want. Set the bowl aside to marinate for at least 15-20 minutes at room temperature. This allows the flavors to penetrate the meat and the cornstarch to work its tenderizing magic.
2. Prepare the Stir-Fry Sauce: In a separate small bowl or liquid measuring cup, whisk together the beef broth, ¼ cup of soy sauce, oyster sauce, honey, rice vinegar, and the remaining 1 teaspoon of sesame oil. In a tiny separate bowl, mix the remaining 1 tablespoon of cornstarch with 2 tablespoons of cold water to create a slurry. Set both the sauce mixture and the cornstarch slurry aside near your cooking area.
3. Cook the Vegetables: Heat 1 tablespoon of vegetable oil in a large skillet, wok, or Dutch oven over medium-high heat. Once the oil is shimmering, add the sliced onions and bell peppers. Stir-fry for 4-5 minutes until the vegetables are crisp-tender. You want them to be cooked through but still have a slight bite and vibrant color. Avoid overcooking them into a mushy state. Once cooked, use a slotted spoon to transfer the vegetables to a clean plate and set aside.
4. Sear the Beef: Add the remaining 1 tablespoon of vegetable oil to the same skillet, still over medium-high to high heat. Allow the pan to get very hot. Carefully place the marinated beef in the skillet in a single layer. It’s crucial not to overcrowd the pan, so you may need to do this in two batches. Let the beef sear undisturbed for 1-2 minutes per side until it’s nicely browned and has a delicious crust. The beef will cook very quickly. Remove the seared beef from the skillet and place it on the plate with the cooked vegetables.
5. Build the Sauce: Reduce the heat to medium. Add the minced garlic and grated ginger to the now-empty skillet. Sauté for about 30 seconds until fragrant, being very careful not to let them burn. Aromatic and pungent, this step builds the flavor base of your sauce.
6. Combine and Thicken: Pour the prepared stir-fry sauce mixture into the skillet, using a whisk or spatula to scrape up any browned bits (fond) from the bottom of the pan—this is pure flavor! Bring the sauce to a gentle simmer.
7. Final Assembly: Once the sauce is simmering, give your cornstarch slurry a quick re-stir (as the cornstarch will have settled) and slowly pour it into the skillet while constantly whisking. Continue to cook and stir for 1-2 minutes as the sauce thickens to a beautiful, glossy consistency that can coat the back of a spoon.
8. Bring It All Together: Return the cooked beef and vegetables to the skillet with the thickened sauce. Gently toss everything together until the beef and peppers are fully coated in the glorious sauce and heated through, about 1-2 minutes. Turn off the heat.
9. Serve Immediately: To assemble the bowls, spoon a generous amount of fluffy cooked rice into each bowl. Top with a hearty portion of the beef and bell pepper mixture, making sure to drizzle plenty of the delicious sauce over everything. Garnish with toasted sesame seeds and sliced green onions, if desired, and serve hot.