Scallion oil noodles (Congyou banmian)

1. Wash the spring onions, dry them thoroughly and cut into 6-8 cm lengths, keeping the white and green parts separate.

2. Heat the oil in a small frying pan over medium-low heat, add the white parts of the spring onions and fry for 3-4 minutes, then add the green parts.

3. Fry slowly, stirring, for another 8-10 minutes until the spring onions are deep brown and crisp but not burnt; lift them out and leave the oil in the pan.

4. Pour the soy sauce and sugar into the oil – careful, it spits – and bubble for 1 minute until the sugar dissolves and the sauce thickens slightly.

5. Cook the noodles in the water according to the packet, drain and immediately toss them with the warm scallion-soy oil.

6. Divide between bowls, pile the crispy spring onions on top and serve immediately.

Tip: One of Shanghai's simplest yet most beloved dishes, made from just a handful of ingredients. You can make a double batch of the scallion oil: it keeps in a jar in the fridge for a week and is heavenly on rice and eggs too.