To prepare stir-fry: Heat a 14-inch flat-bottom carbon-steel wok over high heat. (You’ll know it’s hot enough when a bead of water vaporizes within 1 to 2 seconds of contact.) Add 1 tablespoon oil and swirl to coat. Add chicken and toss until seared and just cooked through. Transfer to a large plate.
Swirl in another 1 tablespoon oil and add vegetables from stir fry kit. Toss to cook until vegetables are tender, about 4 minutes.
Return the chicken to the wok. Add the sauce from the kit and cook, gently stirring, until well coated and hot, 1 to 2 minutes.
Serve over warm brown rice and garnish with cilantro.