Lacto-fermented fruit-based sauces

One of my favourite ways to use lacto-fermented fruits is in sauces. They’re easy to prepare and can be used to create a wide range of sauces, both sweet and savoury, and they add an interesting tang that you get from lacto-ferments.

Method

Mix fruit with 2% salt and add to a sealed jar or vacuum bag. Vacuum bags help with preventing mold as they create an anaerobic environment, perfect for lactobacillus, but if using a jar, make sure the fruit is submerged in the brine, either by squishing the fruit to release its juice or topping up with water mixed with 2% salt. Burp the jar as CO2 starts to build pressure. Vacuum bags puff up, which is fine, just open them if they get too tight.

Ferment for 2-3 days at room temperature. The time will change depending on room temperature, in cooler temperatures, they will need a little longer. I like to stop before it gets too sour, otherwise the tang can be a little overpowering, and all you can taste is the fermented funk. Or you could ferment it longer and really lean into the tang.

Separate the fruit from the brine, keep both.

The brine is useful in small quantities for making your sauces, too much of it will make it really salty. The fruit itself is already quite salty. For the rest of the brine, I mostly use it to season parts of meals, like dressings, yoghurt dips, etc.

For using the fruit, think about where the added sweetness from the fruit and the tang from the lacto-ferment would be useful. It’s worth experimenting. I usually ferment enough at a time to be able to try a couple of variations to see what I can come up with.

Example Sauces

With a recent batch of lacto-fermented blueberries and raspberries, I made two very different sauces.

Blueberry “BBQ”

The fruit replaces some of the acidity you’d normally get from the vinegar and brings some sweetness. I made it like a standard BBQ sauce, with onion, garlic, tomato paste, paprika, brown sugar, Worcestershire, swapping part of the vinegar for the lacto blueberries and raspberries and a splash of the brine. And a Pasilla de Oaxaca chile, toasted and soaked, gives it a smoky heat. Blended smooth and added a splash of water to get the consistency I wanted. In the past I’ve used xanthan gum to help with thickening and it helps a little with stabilising the sauce.

Blueberry and pine

A simple sweet sauce I served with a lemon posset. Pine cone jam syrup added hints of resin that worked well with the tang from the lacto-ferment. Simmer the fruit down with brown sugar and syrup, blend, then finish with cold butter for gloss.