I’ve been reading Sandor Katz’s Art of Fermentation on and off for about six months; it’s an absolute treasure trove of information covering more types of fermentation than I even knew existed. It’s also pretty boring so takes time and concentration to read.

I’ve done a few experiments from it, some successful some not so much. This hot and sour fermented chili sauce is version three of a rough formula outlined in the book (the methods in the book are less recipe and more meandering discussions of possible variations of endless possibilities).

You can vary which chilies you use depending how hot you want it, I currently have a plain red chili sauce which is no hotter than Tabasco, and one spiked with scotch bonnets and habaneros which is quite fiery. No two ferments are the same so it’s always exciting to see how the finished sauce will be.

I’ve made this recipe in percentages, meaning the total weight of your chillies = 100%, everything else is a percentage of the chili weight.

Chillies 100%
Garlic 5%
Ginger 2.5%
Toasted, ground and sieved Sichuan pepper 0.5%
Sea salt 2%

Remove the stems from the chillies and finely slice them and add to a metal bowl. Mince the garlic and ginger and add to the chillies.

Sprinkle over the salt and Sichuan pepper, then start mashing it all together; I use the flat end of a rolling pin, you need to mash it for about ten minutes to break down the cell walls of the chili and let the juices out and the salt in.

After ten minutes you will end up with a kind of wet, chili paste, your eyes will stream and your skin will burn.

Transfer the mixture to a suitably large preserving jar. This mashed chili mixture has enough salt to keep bad microbes away but not too much to kill the natural yeasts and good bacteria that live in the chillies. At warm temperatures this will start fermenting in a few hours, in winter it could take a day or so.

Once the chili sauce starts fermenting, lactic and acetic acid is produced, this adds a delicious sharpness to the finished sauce, but also makes the sauce hostile to bad bacteria such as those that cause botulism. The sauce is essentially pickled.

This can ferment for anywhere between two and four weeks, it’s difficult to taste in this state so you need to decide how sour you want the sauce to be, closer to four weeks it will be more sour than at two weeks. Eventually the yeasts and bacteria will run out of food, or the sauce becomes too acidic, and fermentation will stop.

The following picture was taken at 3 weeks, fermentation had almost finished, probably because it was 30+ degrees for most of the three weeks (warm things ferment faster)

When ready, blitz the chili sauce in a food processor and pass through a sieve. You’ll end up with a sauce with the consistency of Tabasco, but infinitely more flavor. Bottle and store in the fridge; the flavor will continue to change(improve?) for many months as it continues to slowly ferment. Keeps for at least three months, probably years.