Take rice and urad dal, wash nicely. Soak them with sufficient water for at least 4-5 hours. Drain excess water. Add curd and grind to a smooth paste. The batter consistency should be a little thick.
Keep this batter in a warm place for at least 5-6 hours. This batter may not rise as generally we see for Idli batter, but no problem, it will work perfectly.
Mix the dhokla batter nicely. Take a portion of batter, add salt, 2-3 tsp water and beet puree. Mix Well. Once the steamer gets hot, add a spoonful of Eno to the batter. Mix very nicely.
Now immediately pour this batter on hot greased plate. Cover the lid and allow it to cook for 6-8 minutes. After this time, open the lid, if the dhokla is bit firm pour green chutney on it, spread nicely and cover the lid.
Take another portion of the batter. Add salt, 2-3 tsp of water and mix well. Add Eno, mix it and pour on chutney layer. Cover the lid and allow to cook for 8-9 minutes. Before taking the dhokla out, always do the toothpick test.
If toothpick comes out clean, take the plate out and allow it to cool completely. By that time lets make another 2 layers. make sure to use same sized plates for perfect assembling.
Take a portion of the batter. Add Salt, 2-3 tsp water and green chutney and mix well. Add Eno and pour on hot greased plate. Cover the lid and allow it to cook for 5-6 minutes. Take a portion of the batter.
Add salt, 2-3 tsp water, turmeric powder and mix well. Add Eno and pour on the green layer. Cover the lid and cook for 7-8 minutes. Do the toothpick test, take the plate out and allow it to cool completely.
Now Assemble: take a big plate, turn out the dhokla plates carefully as we do for baked cakes. Tap from the back and it will come out. Arrange them properly. I applied a little butter on the white layer then placed green and yellow layers.
Applying butter ensures dhokla will stick nicely and will add a little moisture to taste. At this stage one can microwave for 1-2 minutes or put in the hot steamer for 3-4 minutes. (Its optional, not compulsory) Now temper the dhokla.
Take Oil in a kadai, add mustard seeds. Once it starts crackling add red dry chilli, curry leaves, sesame seeds. Add hing and spread this temper on dhokla. Now with a big, sharp knife cut dhokla with desired shape. Square or diamond.
Sprinkle coriander and serve. Serve with green coriander chutney or Tea / Coffee or Tomato ketchup.