Wash, peel, and roughly cut the carrots and beetroot into pieces.
In a large glass or ceramic jar, add chopped carrots and beetroot pieces.
Now add crushed mustard seeds, black salt, red chili powder and hing.
Pour hot water over the mixture into the jar, stir well to dissolve the salt.
Cover it with a muslin cloth or a loose lid.
Keep the jar in a warm, sunny place for 3-4 days, stirring it once daily.
The fermentation process depends on the temperature; it may take longer in colder weather.
Once the kanji develops a tangy flavor, refrigerate it and serve chilled.