Place everything but the salt in a large heavy bottomed saucepan.
Bring it slowly up to heat and cook it gently for 30 minutes, covered half, half uncovered, stirring once in a while, until everything is delightfully soft.
Taste and salt as you wish.
Swizz in a food processor until smooth.
Transfer it to sterile jars. The ketchup should last for a good few months; refrigerate once opened, where it will be good for a month or so.
