Start by making the sauce. In a small bowl, mix together the cornflour, soy sauce and Chinese rice wine, until the cornflour is fully incorporated.
Add the kecap manis, hoisin sauce, vegetable stock, sesame oil and white pepper. Mix together to combine, then set side.
Boil the chow mein noodles as per the packet instructions, then drain and run under cold water to stop them sticking together.
Heat the oil in a wok over a high heat. Add the mushrooms, season with salt and pepper and stir-fry for 3 minutes, until the mushrooms are soft.
Add the onion, garlic and carrot, and stir-fry for a further 3 minutes, regularly tossing everything together with a spatula.
Add the red pepper, cabbage, beansprouts and spring onion and fry again for 2 minutes, keeping everything moving in the wok with your spatula.
Add the noodles and pour over the chow mein sauce.
Stir-fry everything together for 2-3 minutes, tossing regularly with a set of tongs, until the noodles are hot.
Serve topped with spring onion, sesame seeds and chilli flakes.