In a large bowl mix together semolina, yogurt, ginger paste, green chilli paste, turmeric powder and salt and mix well. Add water and soda and mix well.
Heat oil in a non-stick pan. Add mustard seeds, cumin seeds and curry leaves and saute for a minute.
Pour in the batter and cover the pan and cook on high heat for five minutes and then lower the heat and cook for more five minutes.
Open the lid and turn the cake and simmer for ten minutes.Remove and put the cake on a plate.
Put sauce on top. Put onions, coriander leaves and nylon sev and cut into small pieces and serve.