Heavenly Seafood Soup

Rinse the mussels and clams thoroughly under cold running water to remove sand and grit.
Scrub the shells with a stiff brush and remove the beards from the mussels.
Tap any open molluscs gently with the back of a knife; discard any that do not close.
Rinse again and set aside.
Peel and devein the prawns, then rinse and pat them dry.
Cut each prawn into 3 segments and set aside.
Cut the ginger into 4–5 slices.
Peel the onion.
Combine the chicken stock, ginger, whole onion, and peppercorns in a pan.
Bring to a simmer, then cover and simmer gently for 15 minutes.
Strain the stock into a clean pan, season with salt to taste, and keep warm.
Melt the butter in a wide, heavy pan.
Add the flour and cook, stirring, over low heat for 2 minutes, until the mixture bubbles but does not brown.
Gradually pour in the hot stock, whisking rapidly to prevent lumps.
Simmer gently for 3–4 minutes.
If any lumps appear, strain the mixture at this point.
Add the mussels and clams to the soup and bring to a boil.
Cover and cook over medium heat for 5 minutes, or until the shells open.
(If some do not open, cook for another minute, then discard any that remain closed.
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Add the prawns, crab meat, and coconut milk to the soup.
Cook over low heat for 1 minute.
Serve the soup in wide soup plates, garnished with chopped parsley.