Fermented Red Onions
As we move into the cooler months, supporting your immune system becomes more important. One of the simplest ways to do that is through traditionally fermented foods.
Fermented red onions are a beautiful place to start. Through the fermentation process, natural lactic acid bacteria develop, helping to support gut health, which plays a key role in overall immunity. Red onions themselves are also rich in prebiotic fibres, which feed beneficial gut bacteria, along with compounds like quercetin, known for its antioxidant and anti-inflammatory properties.
This simple ferment feeds your gut and introduces beneficial microbes all in a form that’s easy to add to everyday meals.
What You'll Need
-
1 clean pickle jar - 3–5 red onions (depending on size)
- ½ tbsp whole peppercorns
- 2 bay leaves
- Filtered or spring water
- Quality sea salt
For the brine:
- 2% salt brine (e.g. 2g salt per 100ml water)
Method
Slice your red onions finely and set aside. Cut one thick round from an onion, this will be used to help keep everything submerged.
Add the onions, peppercorns, and bay leaves into your jar. Pack them down gently.
In a separate container, dissolve your salt into filtered water to create a 2% brine. Pour this over the onions until everything is fully covered.
Place the thick onion slice on top to help keep the onions submerged under the brine.
Seal the jar and leave it to ferment at room temperature for 12–15 days.
For the first 5 days, "burp" the jar once daily by briefly opening the lid to release the natural CO₂ buildup from fermentation.
Over time, the onions will transform into a full-bodied ferment, sweet, salty, and sour, with a beautiful depth of flavour.
Why each element matters
- Clean jar: Unlike pickling or canning, you don’t need a fully sterilised jar. Clean is enough. The fermentation process naturally creates an environment where beneficial bacteria thrive and unwanted microbes are inhibited.
- Salt (2% brine): Creates the right conditions for lactic acid bacteria to grow while keeping harmful bacteria at bay.
- Quality sea salt: Provides trace minerals and avoids additives that can interfere with fermentation.
- Filtered or spring water: Chlorine in tap water can disrupt fermentation, so clean water is important.
- Bay leaves: Contain tannins that help maintain a good crunch by supporting cell structure.
- Peppercorns: Add flavour and assist in preservation.
