In a large bowl, mix 2 tablespoons cornstarch with 3 tablespoons water. Add the beef and toss to coat.
In another bowl, whisk remaining cornstarch with soy sauce, brown sugar, garlic, and ginger. Set aside.
Heat a large pan over medium heat and add 1 tablespoon oil.
Add the beef and cook until nearly done, stirring frequently. Remove and set aside.
Add remaining oil to the pan, then cook broccoli and onions for about 4 minutes until tender.
Return the beef to the pan and pour in the sauce.
Bring to a boil and cook for 1 minute until the sauce thickens.
Serve your Easy Beef and Broccoli hot with rice or noodles.