In a mixing bowl, mix together the besan, turmeric and salt. Add water gradually to form a batter of flowing consistency (not too thick or too runny). Cover and rest for 10 minutes
In the meanwhile, prepare your steamer or place a pot of water with a stand (water shouldn't cover the stand) and set it to boil over medium heat.
To the gram flour mixture, add in the fruit salt (or baking soda)* and give it a gentle mix. Pour the batter into a greased cake tin and set it to cook (covered) in the steamer, for 30 minutes over medium low heat
Once cooked (toothpick inserted in the centre should come out clean), run a knife around the edges of the tin and remove the dhokla on a plate. Let it come to room temperature
Heat a small frying pan with the oil, add the mustard seeds and wait for it to splutter. Then add the curry leaves and chilis, once fragrant add the water, salt, sugar and lemon/lime juice, mix well. Once it comes to a simmer and the sugar has dissolved, turn off the flame and add in the coriander leaves
Cut the dhokla in diamonds and pour the tempering evenly all over it. Garnish it with some grated coconut and serve your khaman dhokla with sweet and spicy chutneys. Enjoy!