Indian
Rinse the rice and urad dal and soak them in separate bowls for 5 hours, adding the fenugreek seeds to the dal.
Grind the dal to a fluffy paste and the rice to a slightly grainy paste, using about 450 ml of the soaking water in total, then mix them with 9 g salt. Cover and leave to ferment overnight in a warm place until risen and slightly sour.
For the filling, boil the potatoes for 20 minutes until tender, then peel and crumble them roughly.
Heat 2 tbsp oil in a pan, fry the mustard seeds until they pop, then add the chana dal, curry leaves, chilies and ginger and cook for 1 minute.
Add the onions and cook for 6-8 minutes until soft, then stir in the turmeric, potatoes, remaining salt and 120 ml water and cook for 3 minutes; finish with the cilantro.
Heat a flat griddle over medium-high heat, pour a ladle of batter (about 120 ml) into the center and spread it outward in a spiral into a thin 25 cm round.
Drizzle 1 tsp oil around the edge and cook for 2-3 minutes until golden and crisp, then spoon filling onto one half, fold and serve with sambar and coconut chutney.