Wash the thinai / foxtail millet and soak it in water for at least 2 hours.
Drain the water and place the millet in the blender. Add just enough water to grind it into a smooth paste.
Add the powdered jaggery, rice flour and wheat flour in the blender as well and grind it to a smooth batter.
Remove the batter to a bowl and add the coconut, cardamom powder, salt and the mashed banana. Mix well and let it sit for 3 to 4 hours.
I added the jaggery directly to the blender, but if your jaggery has impurities, then boil it in little water and strain the jaggery syrup and use it to make the batter.
Adjust the consistency of the batter by adding little water. The batter should be thick and pouring consistency.
Once the batter has fermented, mix it well and add the baking soda. Mix it once again.
In the meantime, heat the paniyaram pan and grease each mould with little oil/ghee. I use a combination of both ghee and oil.
Pour the batter into each hole of the paniyaram pan and cook it in low to medium flame until it cooks on one side. Flip it to the other side and cook on that side as well. I cover the pan when cooking to make sure that the inside of the paniyaram cooks well.
Remove the paniyaram and serve warm.
The paniyaram could be heated in the microwave for few seconds when serving at a later time.