Step 1: In a medium bowl, combine the thinly sliced beef with 1 tsp soy sauce and 1 tsp cornstarch. Mix well and let it marinate for at least 10 minutes while you prepare the other ingredients. This tenderizes the beef and helps create a slight crust when cooked.
Step 2: In a separate small bowl, whisk together 1 tbsp soy sauce, beef broth, oyster sauce (if using), brown sugar, grated ginger, minced garlic, and sesame oil. This is your delicious stir-fry sauce. Set aside.
Step 3: Bring a pot of water to a boil. Add the broccoli florets and blanch for 2-3 minutes, until bright green and tender-crisp. Immediately drain and plunge into an ice bath to stop the cooking and preserve the color, then drain again.
Step 4: Heat 1 tbsp vegetable oil in a large wok or skillet over high heat until shimmering. Add the marinated beef in a single layer (cook in batches if necessary to avoid crowding the pan). Sear for 2-3 minutes per side until browned. Remove the beef from the pan and set aside.
Step 5: Add the remaining 1 tbsp vegetable oil to the hot pan. If the pan looks dry. Add the blanched broccoli and stir-fry for 1-2 minutes until heated through. If desired, you can add a tablespoon of water or beef broth to create some steam to help cook the broccoli further, if it's too crisp for your liking.
Step 6: Return the cooked beef to the pan with the broccoli. Give the prepared sauce a quick stir and pour it over the beef and broccoli. Stir continuously for 1-2 minutes, allowing the sauce to thicken and coat all the ingredients. The cornstarch from the beef marinade and in the sauce will help create a glossy finish.
Step 7: Serve immediately over freshly cooked white or brown rice. Enjoy your homemade Beef and broccoli recipe!