How to Make Fermented Lentil Soup

When I first published this fermented lentil soup in Insane in the Brine: The Official Cookbook, it was one of those recipes a lot of people told me warmed them in the winter! But the funny thing is that it’s not exclusively a “winter soup” in my opinion. It has this clean, bright tang that makes it just as good in July as it is in January. (If you want to skip all the google ads chaos, all my recipes have an ad-free, text-only .jpg recipe card at the very bottom.)

What makes this soup different is the fermentation step. Lentils are already cooked, which means they’re basically sterile — no lactic acid bacteria (LAB) left to do the work. So the trick is adding a handful of fresh vegetables to the jar. Those raw veg carry the naturally occurring LAB that kick off fermentation, acidify the lentils, and build that layered, savory tang you normally try to fake with lemon juice. Fermentation also breaks down some of the tougher carbohydrates in lentils, making them easier to digest and helping you absorb more of their nutrients.

The result is a soup with real depth — not just “sour,” but rounded, complex, and a little addictive. It’s nourishing, it’s easy, and it’s one of those recipes that quietly teaches you how powerful fermentation can be in everyday cooking.

So let’s do this!

Yield:

6-8 servings

Shelf life:

2 weeks (refrigerated); 6 months (frozen)

Equipment:

• Large saucepan
• Colander
• Knife & cutting board
• Blender (or immersion blender or food processor)
• Suggested: canning funnel
• Measuring cups & spoons
• Half gallon jar & airlock

Ingredients:

• 1 lb. dry (uncooked) red lentils (454g) & 12 cups filtered or distilled water
• ¼ lb. carrots, peeled & sliced (113g)
• 1 red, orange or yellow bell pepper, seeded & chopped
• ½ onion, coarsely chopped
• 4 cloves garlic, peeled and quartered
• 2% additive-free salt by net weight of the above produce (or 1.5 TBSP salt)

After the ferment:

• 2 cups vegetable broth (can sub with chicken or beef bone stock – that recipe is in the first cookbook too, click here!)
• 1 cup coconut cream
• 1 TBSP curry powder
• 1 tsp sugar (optional)
• ½ tsp black pepper
• ½ tsp ground coriander
• ½ tsp ground cumin
• ¼ tsp turmeric powder
• Pinch cinnamon
• Garnish: fresh chopped cilantro or parsley when serving; dash of fresh coconut cream

Directions:

1. Rinse the lentils and remove any discolored pieces or debris. Bring the water to a boil in the saucepan, then add the lentils. Reduce heat to low and simmer for about 20 minutes, until lentils are soft. Then drain in colander. Allow the lentils to cool to room temperature.

2. In a blender, combine the lentils, salt, onion, pepper, garlic and carrots. Blend until a smooth paste has formed. Using the canning funnel, transfer the paste to the jar and add the airlock/lid. Allow to ferment until the mash begins to form air pockets and puffs up, about 2-3 days (longer ferments are fine but I find it starts to get too sour for my tastes).

3. When ready, transfer the fermented mash to the saucepan and add the broth and seasonings. Stir and bring to a simmer. Stir once, cover and simmer for 20-30 minutes. When finished, turn off and remove from heat, and stir in the coconut cream.

4. For a smooth soup, transfer to the blender (in batches as needed) and blend on high for a minute. When serving, gently stir in a couple additional tsp coconut cream for a nice visual effect (and to further balance the acidity) and garnish with chopped parsley or cilantro. You may opt to add a squeeze of citrus juice and/or salt to taste, but you may find this to be totally unnecessary.