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Valerie O'Connor

Fermented tomato ketchup

Have you always wanted to start fermenting foods? This is a great place to start.

Serving: Makes 900g



  • 2 x 450g jam jars, sterilised
  • 1 x 450g tin of tomato paste/purée
  • 150g honey
  • 50ml water
  • 2 tablespoons whey
  • 2 tablespoons apple cider vinegar
  • 1 pinch cayenne pepper
  • 1 pinch cinnamon, optional
  • 1 pinch black pepper
  • 1 teaspoon salt


1 Combine all the ingredients in a large bowl or jug, whisking the mixture until it becomes nice and smooth.
2 Decant it into the clean jars and pop on the lids. Don’t fill them right up to the top as the mixture will expand.
3 Leave the jars to ferment over a few days (about 3-6) on your kitchen counter, which is ideally a bit cosy. Putting them on a tray is good in case of spillages. If you think the kitchen is too cold, putting the jars in the airing cupboard will speed up the process. A temperature of 18-20 degrees is best.
4 Open the jars once a day to let the gasses escape.
5 After a week the ketchup is ready to eat. It will be tangy as ketchup already is, but you can be smug in the knowledge that you made this yourself and it’s good for your gut too.

Recipe and Photography Credit: Valerie O'Connor 

For more information on Fermentation, check out:

Fermented Beet Kvass

Fermented Whole Grain Mustard


Open the jars with a cloth in case of spitting.