Mix all the ingredients for dhokla except Eno and oil. Mix till you get a smooth paste.
Take a large, thick bottom utensil with a lid. Put some water in it.
Heat water in a large saucepan. Now put a metallic bowl in the middle of the water and turn on flame. Cover the large utensil with its lid wrapped in a clean kitchen towel. Let it pre heat for 2-3 minutes.
Take a smaller aluminium mould or thali which fits into the big utensil that we have put to pre heat. Grease it with some oil.
Now back to the besan mixture, add the Eno to the batter and mix well and you will see that the batter will double in volume. Pour it in the mould, put the mould in the big utensil to steam.
Let it steam on medium flame for 12-15 minutes (mine was ready in 12 minutes). Remove from fire and let it cool.
Prepare the tempering while waiting for the dhokla to steam. In a frying pan, put some oil, when it heats a little, add hing and mustard seeds. They the seeds start crackling, add the cumin, curry leaves, green chillies and sesame seeds, saute for a minute.
Now add the water and sugar and cook till the sugar dissolves in the water. Remove from heat. Once the dhokla cools for a while, unmould it, cut into square pieces, pour the tempering making sure that you cover all the pieces.
Garnish with coriander leaves and coconut flakes.
Let the tempering soak for 10 to 15 minutes