Boil the soaked black gram in a pressure cooker till it is tender (I added a pinch of baking soda to the chickpeas before cooking them to soften them). Drain the black gram but do not throw out the liquid.
Heat the mustard oil in a wok. When the oil is hot, add the cooked black gram and salt to taste. Add the cumin, fenugreek, chilli powder, dried mango powder, coriander powder, fennel seeds, and chickpea flour to the wok.
Sautxe9 till you can smell the toasty chickpea flour. Add the asafoetida. Add the water (I used the reserved liquid in which the gram was cooked and added a little more water to make up the quantity), and cook till the curry is slightly thick (like beasn kadhi).
Garnish with coriander leaves. If you feel the curry is too sour, then add the jaggery.