Put the chicken into a mixing bowl and add the dark soy and half the sugar. Mix well and leave to marinade for 20 minutes.
Heat the oil in wok over a high heat. Add the chicken and stir-fry for 4-5 minutes until cooked through and golden.
Chuck the noodles into the pan and add the light soy and fish sauce. Stir-fry for 2-3 minutes until the noodles are soft and a little charred.
Tip the egg into the wok and stir-fry for about a minute until cooked through.
Add the bok choi and spring onions and mix well.
Transfer the noodles to a serving bowl and top with the red chilli and coriander.
Serve immediately with Sriracha, light soy sauce and lime.
