In a liquid measuring cup or small bowl, mix together the rice vinegar, soy sauce, sesame oil, oyster sauce and cornstarch and set aside.
Place a skillet or saucepan over high heat and add the vegetable oil. Once hot, add the chicken flipping it only a few times until golden brown. This may take 8 - 10 minutes.
Toss in the green onions, broccoli, garlic and ginger and cook for an additional 3 minutes stirring constantly.
Pour the mix from STEP 1 over the top and give it a really good stir.
Add the 1/4 cup of water and stir until the liquid has thickened, about 1 -2 minutes.