Heat a pan, do tadka with mustard, urad dhal, curry leaves and very finely chopped green chilly. Add 1 1/2 cups of (bombay) rava. Roast till nice aroma comes (hardly takes 3-4 minutes; need not change its colour). Remove it from stove and place idly cooker with enough water. In the Rava mix, add salt, 1/2 cup curd, 1 inch ginger-grated, 1 tbs chopped coriander leaves and juice from half lemon. Mix well; add little water, if required, to make it to idly batter consistency. Add 1 tsp eno salt and mix well. Pour the mixture in the idly plate and steam it for 10 minutes. Serve hot with chutney of your choice or idly podi.