Set a large frying pan or wok with 1 tbsp sesame oil over a medium heat. Season the chicken, add to the pan and cook for 5 minutes, stirring continuously, until browned on all sides. Tip in the stir-fry veg and cook for a further 2 minutes.
Add the satay sauce and cook for 3-5 minutes more, until the chicken is cooked through and the vegetables are tender.
Meanwhile, peel the courgette into ribbons and put in a bowl with the remaining sesame oil and chopped coriander, if using. Season, toss well to coat and transfer to a large serving bowl with the mango. Top with the satay chicken stir-fry.