3. Wait until the soup is boiling again, add fish into the pot. Leave and do not stir it until nearly done, otherwise the soup will have bad smell. Then season with sugar, fish sauce and tamarind concentrate. (If you do not want to boil the fish, you can fry it and put in the soup instead)
4. Add prepared vegetables and wait until the soup is boiling again and the vegatables done. Remove from heat.
5. Transfer to a serving bowl. Serve immediately with hot steamed rice.