Slice the beef against the grain into thin strips and chop the broccoli into bite-sized florets.

In a medium bowl, whisk together the soy sauce, water, garlic, ginger, and cornstarch until fully combined.

Heat sesame oil in a large skillet or wok over high heat, add the sliced beef and sear for 2-3 minutes until browned.

Add the chopped broccoli to the skillet and stir continuously for another 2 minutes.

Pour the sauce over the beef and broccoli, stirring over medium heat until thickened, about 1-2 minutes.

Serve hot over steamed rice, garnishing with sesame seeds or chopped green onions if desired.