Soak jaggery in luke warm water for 20 minutes (Time depends on the size of the cut jaggery). Strain to remove impurities
In heavy bottomed pan add the jaggery syrup and cardamom powder and bring it boil. Add the banana puree and cook for 2 minutes
Add rice flour and salt to the jaggery syrup - banana puree and mix well to avoid lumps. Cook til the dough separates from the pan and forms a mass
Keep it aside till you can handle the dough. Cover it with a damp cloth
Grease the hand with little water, take a small portion of Kozhukattai and make it into cylindrical shape
Grease the idli mould with little oil. Steam kozhukattai in idli stand or pressure cooker for 8 to 10 minutes