In a mixing bowl, combine 1/2 a cup of water with sugar, salt, citric acid and turmeric powder. Mix it till the sugar and salt dissolve.
Add gram flour (besan) and water and make a smooth batter. Use a whisker to remove the lumps.
Add oil and mix.
Grease a mould and keep it ready. Also, turn on the steamer and let the water come to a boil.
When the water in the steamer starts bubbling, add baking soda to the batter. Mix well and immediately transfer the batter to the mould. Place the mould in the steamer.
Cover and steam for about 20 minutes.
After 20 minutes, insert a toothpick and check. If it comes out clean, the khaman is ready. Else, steam for some more time.
Once the Khaman is ready, remove it and let it cool on the kitchen counter for about 5 minutes.
Then, de-mould it and let it cool completely.