Place the steak in the freezer for 15 minutes, then very thinly slice and place into a bowl. Add the rice wine vinegar and 2 tablespoons of the soy sauce. Stir to coat the beef, and let marinate for 10 minutes.

Meanwhile, combine ½ cup water with the corn starch, mirin, and remaining 2 tablespoons soy sauce with a fork until very smooth. Add the sriracha and oyster sauce and stir to combine. Set aside.

Heat a large skillet or wok to medium-high heat with the oil. When the oil is very hot and nearly smoking, add the steak in one layer and cook for 3-4 minutes, turning once, until browned, crispy at the edges, and just barely cooked through. Remove the steak from the skillet, reserving any juices, and turn the heat on the skillet to medium.

Add the broccoli to the skillet and let cook in the steak drippings for 2 minutes. Stir the broccoli. When the broccoli starts to turn bright green, pour in the sauce - it should bubble and start to thicken almost immediately. If the sauce gets too thick too quickly, reduce the heat and pour in a bit more water to thin the sauce. Let the broccoli cook for just one more minute, then stir in the beef and any juices.

Taste the sauce and add more oyster sauce for salt or sriracha for spice. Keep adding water as needed to keep the sauce a smooth consistency. The broccoli should be tender but still crunchy. Serve over rice, and enjoy!