In a bowl put the sliced beef and all the beef marinade ingredients. Mix well and let it marinate for at least an hour. This step is vital to tenderizing your beef. While the beef is marinating make the sauce. To make the sauce, you need to mix all the sauce ingredients really well and set aside.
Steam the broccoli and instantly shock it in ice water. This will preserve the vibrant green color. Set aside.
Now heat your wok and add about 2-3 tablespoons of any neutral oil. Dear the beef till brown on both sides. Remove and set aside
In the same wok, add your ginger and garlic and let it get fragrant.This should take just a couple of minutes at most. Now add the mirin and sauté. At this point add the sauce and deglaze the wok. Cook the sauce stirring frequently. Make a cornstarch slurry with the cornstarch and water. Pour the slurry into the sauce and stir fast and well. It will get thicker. Finally you will toss in the beef and broccoli and stir well. Garnish with scallions and sesame seeds. Enjoy with steamed rice