Why this recipe works
Kanji is a wild lactic-acid ferment, the same family of process as idli batter, sauerkraut and kimchi. Left in warm water with salt, the Lactobacillus bacteria that live naturally on the vegetables feed on the carrot's sugars and turn them into lactic acid, which is what makes kanji sour and gives its gentle fizz. Because you drink it raw, those cultures are still alive, so unlike a cooked ferment it is genuinely probiotic. The mustard and salt are not just for flavour, they tilt the jar in favour of the good bacteria and against spoilage. It is a live food, and a real one. The honest caveat: it is salty, so it belongs in small glasses, and probiotic does not mean cure-all.
Ingredients
- Black carrots (or carrot + beetroot)4 to 5
- Water, filtered or boiled-cooled1 litre
- Mustard powder (rai)2 tbsp
- Black salt + rock salt1½ tsp
- Red chilli powder½ tsp
- Hing (asafoetida), pinch1
Method
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1
Wash the carrots, peel lightly and cut into thin batons. Use a clean, dry glass or ceramic jar. Do not use a metal one.
Hygiene matters: a clean jar and clean hands give the good bacteria a clear run. Metal reacts with the acid, so glass or ceramic only.
-
2
Add the carrots, water, mustard powder, both salts, chilli and hing to the jar. Stir well. Cover the mouth with muslin and tie it.
Why salt and mustard: the salt and mustard's compounds hold back spoilage microbes while the salt-tolerant lactobacilli get to work. The muslin lets gases escape and keeps insects out.
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3
Keep the jar in warm sunlight for 3 to 5 days, stirring once a day with a clean spoon. It will slowly turn tart and develop a light fizz.
Why the sun: warmth speeds the fermentation. The growing sourness is the lactic acid the bacteria are making; the fizz is the carbon dioxide. Warmer days mean fewer days.
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4
Taste from day 3. When it is pleasantly sour, move the jar to the fridge to slow the ferment. Serve cold; eat the tangy carrots too. Discard if you ever see fuzzy mould.
Safety: a clean sour smell is good. Fuzzy mould or a rotten smell means throw it out and start again. Cold storage keeps the finished kanji stable for a week or two.
Three ways
1 · Classic black carrot
Deep purple, earthy and tart, the traditional winter version.
2 · Carrot & beetroot
When black carrots are out of season, orange carrot with a little beetroot for colour.
3 · Less salty
Use the lower end of the salt and dilute the poured glass with a little water.