Probiotic Red Onions

Blog post description.

3/29/2026

Time Required:
20 min prep + 3 to 5 days fermenting

Difficulty:
Beginner

What You’ll Make:
Approx. 600g vibrant, probiotic-rich red onions

Why This Matters:
For Your Gut: Fermented onions are packed with probiotics, supporting a balanced microbiome and digestive health.
For Your Life: These tangy onions add instant flavour to salads, potato dishes, and grilled foods, and keep fresh for weeks in your fridge.

Ingredients (Supermarket-friendly)

  • Red onions – 600g

  • Garlic – 3 cloves

  • Bay leaves – 3-4 pcs

  • Peppercorns – ½ teaspoon, red and black

  • Cloves – ½ teaspoon (optional)

  • Sea or Himalayan salt – 20g (not table salt)

  • Water – 500ml (filtered or boiled & cooled)

What You’ll Need

Equipment (You probably have this):

  • Clean jar with lid (1L size)

  • Kitchen scales

  • Sharp knife and cutting board

  • Glass GU pot or small Ziploc bag (to keep onions submerged)

Prep Work (5 minutes)

Safety First:

  • Wash hands thoroughly with soap

  • Clean jar with hot soapy water (no need to sterilise if washed in dishwasher). DO NOT use antibacterial detergent as that will affect fermentation

Step-by-Step Instructions

1. Make the Brine

  • In a separate container, mix 20g salt (approx. 1 level tablespoon) into 500ml water

  • Stir and let it stand until completely dissolved

2. Prep Your Onions

  • Slice onions into half rings, 3mm thick

  • Place garlic, bay leaves, peppercorns, and cloves at the bottom of the clean jar

  • Top up with sliced onions

  • Onions should be lightly packed. Pour brine over until completely submerged

3. Seal & Set

  • Place the weight on top (GU jar or brine filled Ziploc bag) and top it over with brine until the liquid is almost reaching the top of the jar

  • Close the lid finger-tight (not super tight to allow some air in) or remove the seal from Kilner jar and close without it

  • Place on kitchen counter away from direct sunlight

  • Put a small plate underneath (it might bubble over)

The Waiting Game

  • Temperature: 18-24°C is ideal. Warmer = faster. Cooler = slower but more complex flavour

Days 1-2: Not much happening yet. Brine might look slightly cloudy. This is normal. You can start tasting
Days 3-4: Tiny bubbles appearing! Brine getting cloudier. Slightly tangy smell developing. Ready to taste again! Will notice slightly more acidic taste than day 1-2.
Day 5: Active fermentation with some bubbles. Cloudy brine. Tangy, slightly sour smell. Ready to be used.

Tasting & Storing

  • Prefer tangier? Let it sit for one or two more days and taste daily until just right. Remember the fermentation will still happen in the fridge

  • Remove the weight and close the lid tightly.

  • Lasts 1-2 months in fridge (keeps improving!).

Ways to Eat This

  • Fresh salads

  • Potato salad

  • Sandwiches and wraps

  • Tacos & nachos

  • Burgers& hot dogs

  • Top up steaks

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