Cut chicken into 1-inch pieces and marinate with 2 tablespoons soy sauce, ½ tablespoon chili vinegar, cornstarch, and ground ginger for 30 minutes.
Heat 2 tablespoons canola oil in a wok over high heat.
Add marinated chicken and cook until browned, then remove from the pan.
Add remaining oil, then stir-fry celery and onions for 30-45 seconds—keeping them crisp.
Return the cooked chicken to the wok.
Add the remaining soy sauce, chili vinegar, and black pepper.
Stir-fry for 15 seconds to combine everything.
Serve immediately and enjoy!