Place corn starch in a medium bowl and gradually whisk in OJ until smooth. Add soy sauce, rice vinegar, honey, garlic and red pepper flakes, season with salt and pepper and set aside.
In pot or wok heat oil over medium-high. Working in batches, cook chicken until slightly browned and cook through. Transfer to plate and set aside.
Add broccoli, carrots, water chestnuts and 1/2 cup water into wok. Cook, partially covered until broccoli is bright green, about 3 minutes. Add chicken back to wok along with cornstarch mixture, bring to a boil and cook until sauce thickens- 2 to 3 minutes.