Start by marinating the beef in soy sauce, cornstarch, and a pinch of salt for 10 minutes.
Heat vegetable oil in a large skillet over medium-high heat.
Add the marinated beef and cook for 3-4 minutes until browned.
Remove the beef from the skillet and set it aside.
In the same skillet, add garlic and ginger, sautéing for 30 seconds until fragrant.
Add the broccoli florets and stir-fry for about 2 minutes.
Pour in the beef broth and bring it to a simmer.
Return the beef to the skillet and mix well with the broccoli.
Add oyster sauce and sesame oil, stirring to combine.
Cook for an additional 2-3 minutes until everything is heated through and the sauce thickens slightly.