Add a pinch of salt , 1/4- 1/2 cup water and boil the grated bottle gourd .
Simmer and cook till lauki softens . Let it cool a bit before adding it to yoghurt .If you have lot of extra water as left over , drain and keep aside . You can use this water to some other dish .
Prepare a tempering . Splutter mustard seeds in oil . Add red chilli and curry leaves . Switch off .