In a medium bowl, whisk together soy sauce, rice vinegar, toasted sesame oil, oyster sauce, and cornstarch. Set aside.
Add oil to a large wok or skillet over high heat.
Add chicken and cook until golden brown, about 8 to 10 minutes.
Add broccoli, green onions, ginger, and garlic and cook for another 3 minutes stirring frequently.
Pour sesame oil mixture over the top and stir.
Add water and stir until mixture has thickened, about one minute.
Serve over rice.