Method

1. In a bowl, mix together the soy sauce, cornstarch, brown sugar, rice vinegar, sriracha sauce, ginger and garlic.
2. Pour half the liquid over the sliced meat in a bowl and mix until all meat is covered in marinade.
3. Reserve the other half of the liquid and set aside.
4. Heat the oil in a heavy skillet or wok over high heat.
5. Add the broccoli, carrots, water chestnuts and spinach; stir for a minute. Remove to a plate.
6. Allow the skillet to get hot again.
7. With tongs, add the meat in a single layer.
8. Spread out the meat as you add it to skillet, but do not stir for a good minute. (You want the meat to get as brown as possible in as short amount a time as possible.)
9. Turn the meat to the other side and cook for another 30 seconds. Remove to a clean plate.
10. Pour the reserved sauce into the skillet along with the beef broth and oyster sauce.
11. Cook over high heat until it starts to thicken.
12. Add the beef and broccoli back into the skillet and toss to coat.
13. Serve over rice or noodles.