The key to this popular sauce is fermenting the chillies for three days to let to develop the sweet, hot, tangy flavours.

1. Put the chillies, garlic, salt and sugar in a blender and whizz to a rough purée.

2. Pour into a sterilised jar or bowl and cover. Leave to ferment for 3 days, removing the lid to allow the air to escape each day.

3. Transfer to a blender and blitz again until very smooth. Add to a saucepan with the vinegar and fish sauce, bring to a simmer and cook for a few min.

4. Taste and adjust seasoning, then pour into sterilised jars. The sauce will keep in the fridge for 2–3 months.

Enjoy!