Take a large bowl and sift the chickpea flour and semolina. Add the rest of the ingredients for the Khaman except the bicarbonate of soda.
Mix everything together ensuring the salt, sugar and citric acid has dissolved.
Taste the batter - make sure it's to your taste and a good balance of sweet, sour and hot. Rest the batter for about 15-20 minutes.
In the meantime place the wok on high heat with the trivet/metal ring enough water to just fall short of the bottom of the pan when it's placed on top. Bring to a rolling boil.
Place the 12" in circumference and 1 1/2 inch deep baking tin, well greased with about 1 tbsp of cooking oil in the wok so it sits on top of the trivet/ring.
Go back to the rested batter and add the bicarbonate of soda and whisk thoroughly until it becomes frothy.
Pour the batter into the pan and cover with the lid on a high heat for 25-30 minutes. Don't be tempted to lift the lid to have a peek or the Khaman will collapse.
After 25-30 minutes, carefully lift the lid off the wok - taking care not to scald yourself as there will be quite a bit of steam.
Test with a skewer as you would a cake - if the skewer comes out clean, it's cooked through. If there's wet batter onto the skewer then steam it for a further 5-10 minutes or until cooked through. Take the pan out carefully and leave it to rest while you prepare the tempered spice topping.
Heat 2 tbsp of oil in a small saucepan and add the mustard seeds; wait for them to pop before you add the asafoetida, curry leaves and sesame seeds. Remove from the heat and leave to cool for about a minute, and then very carefully add the 4 tbsp water.
Pour the fragrant tempered oil and spices evenly over the Khaman and garnish with grated coconut, more sesame seeds and chopped coriander.
Once cool, cut into 1 inch squares and serve with my Lime and Coriander Chutney.