How to Make It
Cut chicken into 1-inch pieces. Combine marinade ingredients in a bowl. Add chicken and stir to coat. Let stand for 10 minutes. Combine sauce ingredients in a bowl; set aside.
Place a wok over high heat until hot. Add 2 tablespoons oil, swirling to coat sides. Add chilies and cook, stirring, until fragrant, about 10 seconds. Add chicken and stir-fry for 2 minutes. Remove chicken and chilies from the wok.
Add remaining 1/2 tablespoon oil, swirling to coat sides. Add garlic and cook, stirring, until fragrant, about 10 seconds. Add celery, bell pepper, and bamboo shoots; stir-fry for 1 1/2 minutes. Return chicken and chilies to wok; stir-fry for 1 minute. Add sauce and bring to a boil. Add cornstarch solution and cook, stirring, until sauce boils and thickens. Add walnuts and toss to coat.