Combine soy sauce, rice wine, and cornstarch in a bowl.
Add the flank steak slices, mix well, and let them marinate for about 15 minutes.
In a large pan, heat olive oil over medium-high heat.
Add the marinated steak slices and cook for about 2-3 minutes until browned.
Remove the steak from the pan and set aside.
In the same pan, add broccoli florets, ginger, and garlic.
Cook for about 3-4 minutes until the broccoli is tender but still crisp.
Return the steak to the pan.
Add oyster sauce, hoisin sauce, and red pepper flakes.
Stir to combine everything thoroughly.
Pour in the water and let the mixture simmer for another 2 minutes.
This helps blend all the flavors together nicely.