Step 1
In a glass jar, combine the cooled boiled water, ground mustard powder, jaggery, red chilli powder, turmeric, black salt, and regular salt.
Step 2
Stir well with a clean, dry spoon.
Step 3
Cover the jar with a muslin cloth and let it sit in a warm, sunny place for 3-4 days to ferment until it tastes tangy and sour.
Step 4
Once fermented, store in the refrigerator to keep it cool.
Step 5
Boil the potatoes until they are cooked but still firm. Peel and scoop balls out of them .
Step 6
South Indian Tadka & Assembly: Heat 1 tbsp oil in a small pan. Add mustard seeds, fenugreek seeds, dry red chillies, and asafoetida.
Step 7
Once the seeds splutter, add the curry leaves and fry for 5 seconds.
Step 8
Pour this hot tadka immediately into the fermented kanji water and stir well.
Step 9
Soak the aloo balls in the kanji for at least 1–2 hours before serving to let them soak up the flavors. Serve chilled