Blend half the tomatoes, the chillies, garlic, ginger and fish sauce to a fine purée in a blender. Although some people have an aversion to seeds, I wouldn’t strain this as the tomato seeds provide the pectin that will make the jam set. Put the purée, sugar and vinegar in a deep pot and bring to the boil slowly, stirring all the time. When it reaches the boil, turn to a gentle simmer and add the remaining tomatoes, which you have cut into 5mm (⅕in) dice, seeds, skin and all. Skim off foam and cook gently for 30—40 minutes, stirring every 5 minutes to release the solids that settle on the bottom. Also, be sure to scrape the sides of the pot during cooking so the entire mass cooks evenly.
When it’s done, pour into warmed glass jars and allow to cool to room temperature before storing in the fridge or a cold larder for later use.
© 1997 Peter Gordon. All rights reserved.