Skin and chop the tomatoes and finely chop the onions, celery and chillies. Then deseed, core and dice the red pepper. Put vinegar, sugar, salt and mustard seeds in a large heavy based sauce pan, bring to the boil untill the sugar dissolves.
Add the vegetables (including sweetcorn), bring back to the boil and cook for 30 minutes - stirring frequently. Cook until it is thick and pulpy. Leave to cool and place in jars until needed. Enjoy!
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