Mix rawa, curd, ginger paste n salt well, add little water to form semi thick batter. Keep aside for 45mins to an hour. The rawa will soak water and the batter will become thick, now add oil n water enough to form a batter thicker then the idli batter.
Grease the plate to make dhoklas.
Now add baking powder n eno to the batter, mix it well and pour the batter in the greased plate. Steam for 30 mins on medium flame.
After 30 mins insert a knife in the centre of the dhokla to check if it fully cooked.
If the knife comes out clean then the dhoklas are ready. If the rawa sticks to the knife then steam it again for 10 mins. Once the dhoklas are cooked you will notice it has left the corners of the plate and even looks a little dry on the top.
Once the dhoklas are done keep it aside to cool before demoulding. The dhoklas may break from centre if you try to demould it while its hot.
Heat oil n add Mustard Seed to it. Let it crackle. Once the crackling is over pour it on the dhoklas. Its ready.
You may add green chillies, curry leaves to the tadka as well.