Instructions

1. De-seed the chillies then coarsely chop. Peel the garlic, lemon grass and ginger, then roughly chop.
2. Put all the chopped ingredients into a food processor. Add half of the tomatoes then whizz until smooth. Transfer this to a heavy-based pan.
3. Process the remaining tomatoes for a few seconds - this half should remain lumpy, then pour it into the pan. Add the sugar and vinegar, then gently bring to the boil. Simmer gently at low heat for about 2 hours until you get a thick jam.
4. Take it off the heat, stir in the fish sauce then pour it into sterilized glass. Seal the jars airtight.