Bring a large saucepan of water to the boil.
Meanwhile, heat the oil in a wok or frying pan until smoking and add the spring onion.
Stir-fry until fragrant and a deep golden-brown, almost burnt.
Transfer the oil and spring onion to a bowl and set aside.
Combine the soy sauces and Chinkiang vinegar together in a large bowl.
Cook the noodles in the boiling water according to the packet instructions.
Drain the noodles and transfer to the bowl with the soy sauce mixture.
Pour the reserved oil and caramelised spring onion over the top and mix thoroughly before eating.
