Make a paste of grated coconut, green chillis and coriander leaves without adding any water.
Beat the curd well adding water to form a smooth sauce like consistency.
Combine the ground paste with the beaten curd and keep aside.
Add half a cup of water to the cubed vegetables (1/2 tsp salt) except the onions and cook till they are half-cooked. Keep aside.
Heat oil in a pan, add mustard seeds and let them pop, add the cumin seeds, methi seeds and let them turn slightly brown. Add the curry leaves, red chillis and asafoetida, turmeric pwd and toss for a few seconds. Add the onions and saute for 4 mts before adding the cooked vegetables (along with left over water if any) and combine well.
Add the curd-coconut mixture to the vegetables and on low heat, cook stirring continuously, otherwise it might curdle. Adjust the salt and cook till the vegetables absorb the flavors and the gravy thickens. Do not boil. Turn off heat. Cover lid and let it sit for a few minutes before serving for the flavors to absorb.
Serve with white rice.