Wash the millet and soak them in about 3 cups of water for four hours.
Wash the lentils and soak them in 2 1/2 cups of water for four hours.
After 4 hours, grind them to a fine batter. You will not need extra water to grind it. But if you do, please add it. Ensure that the batter is neither too thick nor too thin.
Whisk it well for a minute. Then cover and keep it for overnight fermentation.
The next day, add salt and mix well. Add a little water if needed to adjust the consistency.
Heat water in the idli steamer.
Grease the idli plates. Pour portions of the batter into each section.
When the water in the steamer starts bubbling, place the idli plates.
Steam for 15 minutes. After that, remove from heat and let the idlis stay in the steamer for 2-3 minutes.
Then remove the plates. Rest them on the kitchen counter for 2-3 minutes. Sprinkle some water on the plates. That will make it easy to remove the idlis from the idli plates.
Remove and serve them hot with ghee and any chutney of your choice.