Asparagus soup with prawns and egg (Súp măng tây cua)

1. Snap off the woody ends of the asparagus and cut the stems diagonally into 2 cm pieces; peel and finely chop the prawns.

2. Finely chop the shallots and soften in the oil; add the prawns and stir-fry for 1 minute.

3. Pour in the stock, bring to the boil, add the asparagus and cook for 4-5 minutes until tender-crisp; season with fish sauce and salt.

4. Mix the cornflour with the cold water until smooth and pour into the soup, stirring constantly; cook for 1-2 minutes until silky and thick.

5. Off the heat, drizzle in the beaten eggs in a thin stream, stirring slowly in circles, to make fine, wispy "egg ribbons".

6. Serve with coriander, spring onion and plenty of white pepper.

Tip: A legacy of French colonial times (in Vietnamese, asparagus is "western bamboo"), served as a first course at weddings and celebrations. The original uses crab meat; it's excellent with prawns or, if you can find it, tinned crab.