You will need a unniappam or paniyaram pan to make this recipe. 

Soak the rice in water for 2 hours 

Grind the soaked rice, cooked rice and coconut with water till the batter is smooth 

After transferring the batter to a bowl add the baking soda and leave it untouched for 3 hours minimum, this is when the fermenting happens. 

After 3 hours add the all purpose flour or maida along with salt. 

Now temper oil using mustard seeds, chana dal, curry leaves, chilli and asafoetida. 

Add the tempering to the batter and stir. 

Heat the pan and pour the oil. When the oil is semi hot pour the batter to the 3/4 level in the holes. Let them cook for 2-3 min 

Once the unni appams rise turn them using a fork or spoon. 

Leave them in this position for 2 min and remove from the pan. I use tissue paper to absorb the excess oil.