Bring the rice and rice water to a boil, cover and cook on low for 15 minutes; rest covered off the heat for 5 minutes.
Heat the oil in a large skillet over medium-high heat. Brown the beef for 6 to 7 minutes, breaking it into small clumps, then transfer to a bowl.
Add the broccoli and 1/3 cup water to the skillet, cover and steam for 3 minutes. Uncover and let any remaining water evaporate.
Return the beef with garlic and ginger and stir for 1 minute. Mix the soy sauce, oyster sauce, sugar, cornstarch and sauce water; pour into the skillet and bubble for 1 to 2 minutes until glossy and the beef reaches 160°F.
Serve over the hot rice, dividing the broccoli and sauce evenly.