Stir together 2 teaspoons soy sauce, the sherry, and sesame oil in a bowl. Add chicken and toss to coat. Cover and let marinate at room temperature 20 minutes. Meanwhile, stir together water, rice vinegar, sugar, cornstarch, and remaining 3 teaspoons soy sauce; set aside.
Heat 2 teaspoons canola oil in a large skillet over medium-high heat. Stir-fry chicken until nearly cooked through, about 5 minutes. Remove chicken. Add chile peppers, green onions, and remaining 2 teaspoons canola oil to skillet; stir-fry 1 minute. Add bok choy and ginger; stir-fry 1 minute more. Add chicken and soy sauce mixture; cook until bubbling. Sprinkle with peanuts and serve with rice.