In a small bowl, whisk together the peanut butter, coconut milk, stock and lemon zest until blended, then set aside.
Heat the oil in a wok or large frying pan over a high heat. Add the garlic and chilli and stir-fry for 30 seconds to release the flavours.
Add the chicken and five-spice powder and stir-fry for 3–4 minutes until the chicken has coloured all over. Add the red capsicum, carrots and mushrooms and stir-fry for 2–3 minutes until slightly softened.
Pour the peanut butter mixture into the wok and stir-fry for a further 2–3 minutes until the chicken is cooked through and tender. Remove from the heat, stir in the chopped coriander and serve immediately.