Whisk soy sauce, stock, sesame oil, brown sugar, and cornstarch in a small bowl until the mixture is smooth. Set aside.

Heat 2 teaspoons of the canola oil over medium-high heat in a large frying pan or wok. Add the chicken strips and cook, stirring frequently, until cooked through, about 5 minutes. Transfer to a plate and tent with aluminum foil to keep warm.

Add the remaining 2 teaspoons of canola oil to the pan and swirl to coat. Add the red pepper flakes, ginger, and garlic, and cook, stirring constantly, for 30 seconds. Add the broccoli, bell peppers, cabbage, and carrots, and cook, stirring frequently, until crisp-tender, about 5 minutes.

Return the chicken to the pan and stir to incorporate. Add the soy sauce mixture, stir to coat, and bring to a simmer for about 2 minutes, until the sauce is thickened and glossy.

Serve with brown rice.