Heat the oil in a wok over a high heat until smoking.
Stir-fry the ginger, garlic, and chillies for 1 to 2 minutes.
Add the green spring onion parts and stir-fry for 2 more minutes.
Add ketchup, sweet chilli, hoisin, fish, and soy sauces and bring to a boil.
Simmer the sauce for 5 minutes and season with sugar if desired.
Boil the egg noodles according to instructions and drain them.
Set aside 3 ladlefuls of the sauce.
Add the crabmeat to the wok and simmer for 5 minutes until warm.
Divide the crab and sauce into serving bowls.
Toss the noodles, white spring onions, mint, and coriander in the remaining sauce and serve.