Chicken Stock - :
Place 6 litres water in a large pot with the chicken, garlic and a knob of ginger. Bring to the boil and then stand and skim the impurities off the top until they stop appearing at the surface (this is very important).
Strain liquid and add to a clean saucepan.
Combine chicken stock, salt, sugar and fish sauce, mix well and return to the boil.
For the steamboat:
Place the gas stove with a special steamboat hot pot or large saucepan in the middle of the dinner table. Transfer 2 litres of the chicken stock mixture to steamboat.
On separate platters, place vegetables, herbs, seafood and vermicelli.
In small dipping bowls, add sliced chilli and soy sauce for dipping.
Bring the stock to simmer, each person dips some greens and seafood into the stock until cooked.
Each person retrieves their cooked ingredients with their chopsticks then pours some stock into their bowls. As the greens and seafood cooks, the more flavorsome the stock becomes.
When the stock starts to boil down, replenish with remaining liter of chicken stock.