Soak green gram in hot water for 3-4 hours or overnight in regular water; strain it
Cook with 1 cup + 1/2 of water and pinch of salt in a pressure cooker for 2 whistles
Soak jaggery (make small pieces to speed up the process) in 1/4 cup of hot water, After the jaggery completely melts in water, strain the impurities
In a pan, add jaggery syrup and cardamom powder; bring to boil
Add cooked green moong bean to the boiling jaggery syrup and continue cooking
Add coconut and continue cooking till the jaggery syrup is completed absorbed. Add butter towards the end and cook till it becomes Sundal consistency