Start by marinating your beef. In a medium bowl, combine 3 tablespoons of cornstarch and 2 tablespoons of water. Stir until smooth. Add the thinly sliced beef and toss to coat evenly. Let it sit for about 15 minutes while you prepare the other ingredients.
In a large wok or skillet, heat 1 tablespoon of vegetable oil over medium-high heat. Add the broccoli florets and onion to the pan, stirring frequently. Cook for about 3-4 minutes, or until the broccoli is bright green and slightly tender. Remove the vegetables from the pan and set them aside.
In the same pan, add the remaining tablespoon of vegetable oil and heat over high heat. Once hot, add the marinated beef in a single layer. Allow it to sear without stirring for about 1 minute. Then, stir-fry the beef for another 2-3 minutes until it’s browned and just cooked through.
Once the beef is cooked, add the remaining ingredients: ½ cup of water, ⅓ cup of low sodium soy sauce, 2 tablespoons of brown sugar, 1 teaspoon of minced garlic, and 1 teaspoon of ground ginger. If you like a little spice, sprinkle in some red pepper flakes. Stir everything together, allowing the sauce to come to a gentle simmer.
Add the cooked broccoli and onions back into the pan, tossing everything together to coat the vegetables and beef in the sauce. Cook for another 1-2 minutes until everything is heated through. If you’re using sesame oil, drizzle it over the stir-fry just before serving.
