Soak the raw rice in water for 1 to 1½ hour.After 1 hour wash the rice 3 to 4 times and blend it in a mixer along with boiled rice and grated coconut. (Use only ½ cup water for grinding)Transfer the batter (should be grinded thoroughly) to a bowl, add baking soda and keep it aside.In a pan warm the jaggery by adding one cup water to liquid form. Turn off the flame and allow it to cool.Filter the jagerry through a sieve to the batter in the bowl, add cardamom powder and mix well. The final batter should be lighter in consistency than the Dosa batter. This determines the softness of Kalathappam.In a pan warm the batter in low flame (Do not boil but stir it thoroughly while warming) and turn off the flame.Meanwhile in a pressure cooker add coconut oil, ghee, sliced onion, coconut flakes and saute till coconut flakes becomes brownish. (use high flame)Add the batter to the cooker and gently mix with the contents and cover the lid without putting the weight of the cooker.Wait for the steam to escape and then turn the flame to minimum and cook for 20 minutes or until a toothpick inserted into the center of the Kalathappam comes out clean.Separate it from the sides of the cooker using a flat spoon and serve it hot with a cup of tea.