In a bowl add semolina ,yogurt ,sugar,salt,oil and mix well.
Keep aside for 10 min.and then add water and whisk nicely .
Divide into 3 portions and to the first part add carrot puree,baking soda,and pour into a greased cake tin.
Keep the tin in the steamer and cook for 10 min. On a low flame .switch the flame off and take the tin out.
Add water and baking soda to the second part and pour over the saffron colour batter and put the tin back in the steamer again for 10 min.on high fame.
In the third part add spinach puree and baking soda mix well .
Take the tin out of the steamer and pour the final part of the batter.
Put the tin back into the steamer for 10 min.on high flame.
Let the batter come down to room temperature completely .
In a pan heat oil and crackle mustard seeds in it.
Turn the flame off and add asafoetida ,curry leaves,green chillies and stir .
Delicious tricolour dhokla is ready to eat.