Mix the ingredients for the sauce together and set aside. You can do this well in advance and cook as needed. It just takes seconds to thicken in the pan.
Cook the chicken and add to the sauce in a heavy sauté pan and cook until the sauce starts to bubble and thicken. Be careful you don’t over thicken it.
Sauté the pak choi quickly in a separate pan with the rapeseed oil, garlic and soy sauce. This just takes a minute to wilt, so you can do this at the last second.
Sprinkle the chicken with sesame seeds, spring onions, red chillies and coriander and serve hot with the pak choi and some napkins to help with the sticky fingers and mouths.