Amazing Gut Building Lacto-Fermented Onions Recipe

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Fermenting onions is not only a delightful culinary adventure but also a journey toward enhanced health benefits and a sustainable way to preserve your onion harvest. The process of fermentation not only transforms the pungent taste of raw onions but also makes them easier to digest and enriches them with probiotics for a healthy and functioning gut microbiome! The best part? They only take a few minutes of prep work! 

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Health Benefits of Fermented Onions

Fermented onions offer a multitude of health benefits that make them a worthwhile addition to your diet. Onions alone are a huge health benefit with their high antioxidant load benefiting systems such as the cardiovascular and endocrine systems. They contain a ton of vitamins and minerals that help the body function and improve the immune system!

Enhanced Digestibility

Raw onions can be tough on the digestive system for some individuals due to their high fructan content. Fermentation helps break down these complex sugars, making the onions easier to digest and reducing the likelihood of digestive discomfort.

Probiotic Powerhouse

Onions naturally have a ton of beneficial bacteria growing on their surface and in-between all those crunchy layers. By creating a anaerobic environment, the natural sugars begin to break down and produce lactic acid, encouraging the growth of beneficial bacteria, turning your onions into a probiotic-rich food. These probiotics promote gut health, aid in nutrient absorption, and bolster the immune system.

Nutrient Preservation

Unlike traditional cooking methods that can lead to nutrient loss, fermenting onions preserves their nutritional value. You’ll still get essential vitamins and minerals like vitamin C, B vitamins, and potassium.

Improved Flavor Profile

Fermentation mellows the sharpness of raw onions, resulting in a complex, tangy, and slightly sweet flavor. It adds a new dimension to your dishes and can be enjoyed on its own as a condiment.

fermented onions

What Do Fermented Onions Taste Like?

Fermented onions undergo a fascinating transformation in flavor that distinguishes them from their raw counterparts. The fermentation process not only preserves these humble bulbs but also enhances their taste, making them a unique and versatile ingredient in your kitchen.

Initial Pungency

Raw onions, especially when sliced or diced, often have a strong, pungent flavor. This pungency can be overpowering and sometimes deter people from consuming them in large quantities. However, it’s precisely this characteristic that undergoes the most significant change during fermentation.

Mellowing of Sharpness

As the onions sit in their salty brine, the initial sharpness gradually subsides. The process allows the natural sugars in the onions to develop a sweeter and more nuanced taste, balancing the sharp and sometimes bitter notes that can be off-putting to some. This transformation appeals to a broader range of palates.

Complex and Tangy

Fermentation adds depth and complexity to the flavor profile of onions. The tangy notes that emerge during fermentation are reminiscent of the zing found in pickles, creating a delightful contrast to the sweet undertones. This complexity makes fermented onions an excellent accompaniment to a variety of dishes.

Versatile Condiment

The taste of fermented onions is versatile. They can be tangy, slightly sweet, and mildly sour, all at the same time. This versatility makes them a perfect addition to sandwiches, salads, and as a garnish for various dishes, including tacos, burgers, or even grilled meats. The tanginess can provide a pleasant counterbalance to fatty or rich foods, adding brightness and depth.

Texture Transformation

In addition to flavor, the fermentation process also affects the texture of the onions. The initial crispness softens during fermentation, making them tender and more palatable. This change in texture makes them enjoyable to eat both on their own and as a topping or ingredient in various recipes.

fermented red onions

How To Make Fermented Onions

Making lacto-fermented onions is so easy and only takes a few minutes!



  • 1 lb Onions (Red onions are an excellent choice for their flavor and color)
  • 1 1/2 tbsp Kosher Salt
  • 1/2 cup Filtered Water
lacto fermented red onions


  1. Prepare the Onions: Start by peeling off the outer skin of the onions and then slice them as thinly as you desire. You can opt for thicker slices if you prefer more crunch or thinner slices for a softer texture.
  2. Salting the Onions: Place the sliced onions in a large mixing bowl and add the kosher salt. Mix the onions and salt thoroughly until they start to sweat and become somewhat mushy. This helps draw out moisture from the onions and creates the brine needed for fermentation.
  3. Packing the Jar: Once your onions are suitably sweat, pack them tightly into the Mason jar, leaving some headspace at the top. The goal is to minimize the air pockets.
  4. Adding Water: Pour the filtered water over the onions in the jar, ensuring they are completely submerged. Leave a small space at the top to accommodate the fermentation weight.
  5. Fermentation Weight and Lid: Place the fermentation weight on top of the onions to keep them submerged in the brine. Secure the fermentation lid on the Mason jar to allow gases produced during fermentation to escape while preventing air from entering.
  6. Fermentation Time: Store the jar in a room-temperature location, away from direct sunlight, and let it sit for approximately 24 hours. During this time, the fermentation process begins.
  7. Check for Submersion: After 24 hours, check that the liquid in the jar is still covering the onions. If not, add just enough water to ensure they remain fully submerged.
  8. Fermentation Duration: Continue fermenting for 5-7 days, or until you achieve your desired taste and texture. The longer you ferment, the tangier and softer the onions will become.
  9. Refrigeration: Once you’re satisfied with the flavor and texture, move the jar to the refrigerator. Properly stored, your fermented onions can last for 4-6 months.
how to ferment onions

Storing Fermented Onions for Long-Term Preservation

To ensure your fermented onions maintain their quality for an extended period, follow these storage guidelines:

  1. Temperature: Keep the jar of fermented onions in the refrigerator at a temperature of 35-40°F (1.7-4.4°C). Cold storage slows down the fermentation process and preserves the onions.
  2. Airtight Seal: Ensure that the jar’s lid is tightly sealed to prevent the entry of air, which can lead to spoilage.
  3. Regular Inspection: Periodically check your fermented onions for any signs of spoilage, such as off smells, mold, or a slimy texture. If you notice any of these, discard the contents.
  4. Use Clean Utensils: When removing onions from the jar, use clean utensils to avoid contamination. Always return any leftovers to the refrigerator promptly.

For even more fermented veggie recipes, check out our Fermented Carrots and read all about Honey Fermenting!

Happy Fermenting!

Fermented Onions

A delicious soft onion condiment that is loaded with healthy probiotics!
Prep Time15 minutes


  • 1 lb Onions Red makes an absolute delicious ferment
  • 1 1/2 tbsp Salt Kosher
  • 1/2 c. Water Filtered


  • Remove the outer skin and slice the onions as thin as desired.
  • Place the onions in a large mixing bowl, add the salt, and begin mixing until the onions begin to sweat and feel mushy.
  • Pack the onions into the mason jar and pour the water over the top.
  • Place the fermentation weight on top of the onions and secure the lid.
  • Place your fermented in a room temp spot, out of direct sunlight light, and allow to sit for 24 hours.
  • After 24 hours, check on your ferment and make sure the liquid is completely covering the onions. If it's not, add just enough water to cover.
  • Allow the ferment to sit for 5-7 days, or until desired taste and texture is achieved.
  • Store your ferment in the fridge for 4-6 months.

Hey Beautiful! I’m Tara, garden enthusiasts, keeper of chickens, herbal homesteader and stay at home mom of 3 tiny humans and a sourdough starter named Ma. I love teaching others how to live a self-sufficient and sustainable life through homesteading, scratch cooking, and remembering to live barefoot, wild and free!

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