Slice up the lemongrass, galangal, tomatoes, chilies, mushrooms, and shrimp
Pour the water into a pot, add the lemon grass and kaffir-lime leaves and heat it.
Add the shrimps when the water is boiling and cover the pot.
Wait for 3 minutes before adding the mushrooms and salt.
Leave it to simmer for a few minutes. Then remove from the heat.
Season with fish sauce, lime juice and ground chilli.
Put the chopped coriander leaves in the pot before serving.