Wash and soak urad dal + fenugreek seeds for 4 hours. Wash and soak rice separately for 4-5 hours.
Grind urad dal adding water little at a time until smooth and fluffy. Remove and keep it in a vessel.
Grind rice adding water from time to time to a sightly coarse batter.
Now add the urad dal batter, ragi flour and salt to the rice batter and grind everything together until well mixed. The consistency of the batter should be similar to idli batter (neither too thick nor too thin).
Remove from the wet grinder and mix it well with your hands. Leave it to ferment overnight or for 7-8 hours. Use a big vessel to prevent it from over flowing as it will double while fermenting. Our Ragi Idli batter is ready.
Method
Heat water in an idli vessel or steamer. Mix the fermented ragi idli batter well and pour a ladle of batter into the idli molds and place it inside the steamer or idli cooker.
Steam cook for 10-15 minutes or until a toothpick inserted in the center of the idli comes out clean. Once done sprinkle water and remove from the mold after 2-3 minutes.