Place the cabbage, carrots, spring onions in a bowl and cover with water. Add the salt and mix. Leave to soak for 3-4 hours, stirring occasionally.
Drain the vegetables, saving around 1 pint of the salt water in a jug.
Add the ginger, garlic, chilli powder, fish sauce and porridge to the vegetables and mix well.
Transfer the mixture to clean glass jars.
Add enough of the reserved water to cover the vegetables. Press the vegetables down so they are submerged.
Place the lid on the jar and leave at room temperature.
After 24hrs take off the lid and stir. You may notice some bubbles which means fermentation has begun.
Put the lid back on and leave at room temperature for another 2 to 3 days. Stir daily and ensure vegetables remain under the water.
It is now ready to eat. Store in the fridge.