Place 2 pounds thinly sliced flank steak in a zip-top bag.
In a small bowl, whisk together 2 tablespoons cornstarch and 3 tablespoons cold water. Pour the mixture into the bag with the steak and toss to coat. Marinate for at least 20-30 minutes.
Heat 2 tablespoons vegetable oil in a large skillet over medium-high heat.
Add 2 cups broccoli chopped into bite-sized pieces to the skillet. Cover and sauté for 3-4 minutes until slightly tender.
Add the marinated flank steak to the skillet. Sauté uncovered for an additional 3-4 minutes until the beef is cooked through and the broccoli is tender.
In a small bowl, whisk together 1 tablespoon cornstarch, 1 tablespoon minced garlic, 3 tablespoons brown sugar, 2 tablespoons rice vinegar, and ½ cup soy sauce. Pour the sauce over the beef and vegetables and toss to combine. Heat for 1 minute to make sure that all the flavors are combined and heated through.
Remove from heat and serve warm over 6 cups cooked white rice. Enjoy!
Notes
We used flank steak for this recipe, but you can easily use skirt steak or sirloin steak as well. Refrigerate the leftovers in an airtight container for up to 5 days.