Stir together the marinade ingredients until the cornstarch is dissolved. Stir the beef in the marinade until coated and let stand for 10 minutes.
Meanwhile prepare the sauce. Stir together the stock, oyster sauce, rice wine, and soy sauce together in a bowl.
Cook the broccoli in a small pot of boiling water about 2 -3 minutes. Drain thoroughly.
Heat a wok over high and add the oil, swirling to coat the sides of the wok. Add beef and cook until no longer pink, about 1 1/2 - 2 minutes. Add the sauce and broccoli and bring to a boil. Pou in the dissolved cornstarch and cook until the sauce boils and thickens, about 1 minute. Serve.