For Ragi Idli:

Wash and soak parboiled rice for 6-8 hours, similarly wash and soak split skinless black gram along with fenugreek seeds for 6-8 hours in another bowl. Soak poha also for 1 hour in the third bowl.
Drain and blend soaked ingredients with ¾ cup water until smooth. Transfer to a bowl and add ragi flour to it, cover and ferment for 6-8 hours.
Add salt and ¼ cup water to the fermented batter. Mix well.
Heat water in a steamer. Grease the idli mould with oil and pour a portion of the batter in the mould. Steam for 10-15 minutes. Unmould when ready.

For Coconut Podi (Thengai):

Dry roast grated coconut in a pan on low heat until crisp. Set aside.
In the same pan, heat 1 teaspoon oil and roast split skinless black gram and Bengal gram until golden brown. Transfer to a plate and allow to cool.
Dry roast coriander sesame seeds, cumin seeds and fenugreek seeds until they pop. Transfer to the same plate and allow to cool.
Heat remaining oil and add dried red chillies, sauté for a minute. Transfer to the same plate and allow to cool.
Grind the roasted spices in a mixer jar with sea salt and asafoetida, grind to a coarse powder.
Allow the podi to cool on a plate and store into an airtight container.

Mix a portion of podi with ghee. Serve with ragi idli.