Fermented Mexican Salsa

Late summer & autumn often bring with them an abundance of tomatoes, so it’s good to have a few different recipes on hand for how to make the most of the abundance. Of course making chutney is a great way to preserve tomatoes for enjoyment throughout the year, so we always keep recipes for red tomato chutney and green tomato chutney floating about as the days begin to shorten.

But part of the joy of growing your own tomatoes is the delight of eating them fresh and in freshly prepared meals. The flavour of homegrown and vine-ripened toms is unlike any standard shop-bought tomato you will buy. Of course rich sauces and Italian recipes come to mind when you think of ripe red tomatoes, but one of our favourite quick ways to enjoy them is halfway between fresh and preserved: as fermented Mexican salsa!

Why fermentation?

Fermenting is an age-old way of preserving food without refrigeration or cooking equipment, and it has the wonderful side benefit of transforming everyday flavours into tangy, umami-rich, nuanced complexities that would take years of training as a chef to develop. Oh, and fermented foods are also jam-packed with beneficial bacteria, so eating them regularly has been proven to improve gut and subsequent mental health. Pretty great set of recommendations, eh?!

If you’re new to fermenting and feel a bit nervous about it as a preservation method, have a read of this article which hopefully answers a lot of your questions and puts you more at ease.

It’s easier than it seems

Fermented Mexican salsa is great because you can use so many different types of ingredients available at this time of year. Tomatoes, capsicum, chillies, corn, cucumber, spring onions and red onions: these all work wonderfully in a regular salsa, and are utterly transformed by the simple process of fermenting for a few days.

This recipe seems wordy, but is actually very basic – there are no measurements as such, and that’s because it’s something you can make as much or as little of as you like, without any hard and fast rules. The absolute bare bones of the recipe is “Chop up veg. Add 2% salt. Mix. Leave it alone for a few days.”

Use what you have, make the ratios of veg to your taste, and go from there!


  • Tomatoes
  • Onion if some sort
  • Pure salt (see notes)
  • (all optional additions) garlic, capsicum, corn kernels, chillies, cucumber, lime juice, coriander.


  1. Rinse tomatoes. Chop coarsely and add to a bowl.
  2. Peel & dice onions and chop up any other ingredients you fancy adding. Add to the bowl.
  3. Weigh the combined veggie ingredients (minus the bowl weight).
  4. Work out 2% of the veggie weight: to do this, multiply veggie weight by 0.02. Round up any decimals in the answer. Whatever the result, add that many grams of salt. (Eg: 460g veggies x 0.02 = 9.2. Round up to 10. Add 10g of salt.)
  5. Mix veggies & salt well, then stuff into a clean jar. Leave enough space to add a smaller clean jar in the top.
  6. Fill smaller jar with water and use it to push down the veggies. Overnight, the liquid from the veggies will be released, forming the brine which will submerge the veg and enable fermentation to occur.
  7. Cover jar loosely to stop bugs getting in, and leave at room temperature (out of the sun) for a few days until brine goes cloudy, bubbles form throughout, and it smells rich and flavoursome.
  8. Once you like the taste of the salsa, scoop the veggies out of the brine and serve, or if you want a smoother sauce, blitz in a blender with a bit of brine. Make it as coarse or smooth as you like by adjusting how much brine you add.
  9. Whatever you don’t eat immediately, stuff into a clean jar, make sure the veg are covered with brine, seal and store in the fridge for months and months and months.


  • Pure salt is salt that has no additives. Lake, sea, kosher, ‘pickling’, rock: they’re all pure. If measuring by volume rather than weight, make sure to use granulated salt, otherwise the ratios will be off.
  • For fermenting, jars don’t need to be sterilised, as the salt will kill off most bad bacteria. Just give your jar a good wash with hot soapy water and rinse well.
  • Fermentation will take longer in cooler weather, so don’t fret if it takes a week or more for bubbles to form. You could leave this fermenting for up to a month (and very possibly more), so don’t worry about leaving it ‘too long’. Be aware the flavours can develop a yeasty taste after a month – it’s still fine to eat, it just might not be to your taste.
  • We find this salsa is usually ready in 2-3 days in autumn, and in winter it takes around 5 days. We’ll sometimes add a dash of our fermented chilli hotsauce which not only adds heat & flavour, but helps speed the process up a bit thanks to its existing beneficial bacteria balance.

Permaculture Principle 2: Catch & store energy; 3: Obtain a yield; 6: Produce no waste; 9: Use small and slow solutions; 10: Use and value diversity;

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