In a large saucepan, combine the chicken stock, salt, sugar and fish sauce. Mix well and bring to a boil.
Put the gas stove and steamboat hotpot or large saucepan in the middle of the dinner table. Transfer 2 litres of the chicken stock mixture to the steamboat. On separate platters, arrange the vegetables, herbs, seafood and vermicelli. In small dipping bowls, add some sliced chilli and soy sauce for dipping.
When the stock starts to simmer, each person dips some greens and seafood into the stock until cooked. They then retrieve their cooked ingredients with their chopsticks and ladle some stock into their bowls. Dip into soy and chilli.
As the greens and seafood cooks, the more flavourful the stock becomes.
When stock starts to boil down, replenish the pot with more stock.
NotesYou'll need a portable gas stove for cooking at the table and a special steamboat hotpot or a large saucepan.