Into a bowl add the yam, yogurt, ginger paste, green chili paste, turmeric powder, coriander powder, sugar to taste and salt to taste and mash well with a potato masher.
In a pressure cooker pot heat oil and temper mustard seeds, dry red chili, asafoetida and kasoori methi and stir.
Add the suvaran mixture and let it simmer for about 2 -3 minutes.