Wash and soak chana dal for 2 hours in 2 cups of water.
After 2 hours, discard the excess water. Grind chillies and ginger in a mixie.
To this, add the soaked chana dal and grind it to a coarse batter. Transfer this batter to a mixing bowl.
Beat besan and yoghurt/curd in a mixie so that they get well blended. Add this to the Chana Dal Batter.
Add turmeric powder, asafoetida and salt. Now mix this batter well. Cover and leave it for overnight fermentation. The next day, the batter should be well fermented.
In a steamer, add water and let it come to a boil.
Meanwhile, add oil, lemon juice, baking soda and a little water (about 1/ cup) if the batter looks thick. Mix. Whisk the batter for about a minute to incorporate air.
Grease a baking mould. Then, pour in the batter to half the height of the mould.
Place it in the steamer. On high heat, steam it for 15 minutes. After 15 minutes, insert a toothpick and check if it comes out clean. If it does, turn off the heat, remove the mould and let it cool. Suppose the toothpick doesn't come out clean, steam for a few more minutes and check again. When done, remove the mould and let it cool.
Let it cool for at least 15 minutes before you de-mould it.
After de-moulding, cut the Khaman into cubes.
Prepare the tempering by heating oil in a pan. Add cumin seeds, mustard seeds ( not shown in the picture, but you can add them), slit green chillies, curry leaves and asafoetida.
Put this tempering on the Khaman. Use a big mixing bowl to do this. Toss the Khaman and the tempering so that everything gets mixed well. Garnish with fresh coriander leaves and serve with Mint Coriander Chutney.