Bring the fish stock to the boil and add
in the fish sauce. Add half teaspoon of the shrimp paste into the
simmering stock. When cooked,
they will turn opaque and rise to the top. Add cabbage,
bring back to the boil, cover and leave for a minute, or until cabbage
is tender. Sprinkle
spring onions on top and remove from heat at once. Cover and
leave for 1 minute. Serve hot.