Add 2 tbsps of flour to broccolis, fill the basin with cold water and soak the broccoli for 10 minutes.
Cut 500g beef against the grain (see picture illustrations above) into ⅛ inch thick x 1 inch wide x 4 inch long slices.
Transfer sliced beef to a bowl, add ¼ tsp salt, ½ tsp dark soy sauce, ½ tsp black pepper, and ¼ baking soda to the beef. Mix by hand until the color (from dark soy sauce) looks evenly on the beef. Add 1 egg white to the beef. Mix well by hands for about 2 minutes until all the egg white has been absorbed into the beef.
Add 2 tbsps of cornstarch to the beef. Mix gently by hands until all the beef slices are evenly coated with a thin layer of cornstarch.
Add 2 tbsps of olive oil to the beef. Mix gently by hands until all the beef slices are evenly coated with a thin layer of olive oil. (This step can prevent the beef slices from sticking to each other in the frying pan.) Set aside to marinate for 10 minutes.
Rinse the broccoli under running water. Cut broccoli florets into bite-size. Peel broccoli stems, cut them into bite-size.
Optionally (See Note 1), bring half pot of water to a boil over high heat, add in the broccoli, and boil the broccoli for about 1 minute. Use a slotted spoon to transfer the blanched broccoli to a plate. Set aside.
Add all the sauce ingredients (¾ cup warm water, ¼ tsp salt, 1 tbsp oyster sauce, ½ tbsp sugar, 2 tbsp light soy sauce, 1 tsp dark soy sauce, ½ tsp black pepper, ¼ tsp chicken powder (or msg), 1½ tbsp cornstarch) to a small bowl. Mix well until all the ingredients are dissolved. Set aside.
Finely chop 3 garlic cloves and a small piece of ginger.
Add 2 tbsps of cooking oil to a large frying pan, heat up the oil over medium high heat. (See Note 2) Add chopped ginger and garlic to stir fry for 20 seconds. Add marinated beef slices to stir fry until there is no pink spots on the beef slices, transfer the fried beef to a bowl.
Do not wash or wipe the pan, pour in the sauce we just made. Stir and simmer the sauce for about 1 minute until it gets thickened with a glossy sheen.
Add broccoli to the frying pan, stir until all the broccolis are evenly coated with sauce. Add fried beef slices to the frying pan, stir fry for about 30 seconds until all the ingredients are well mixed.
Transfer beef and broccoli to a serving plate. Optionally sprinkle some toasted sesame seeds over the top. Serve immediately with hot steamed rice or fried noodles.