Clean and soak white lentil and millet with fenugreek seeds in some water for minimum 4 hours.
Now grind it using your food processor with enough water to make a smooth batter.
Transfer the content in a pan and add some salt to taste and mix it well. If you feel the batter is too thick add some more water. Do not make the batter too runny, it should be of pouring consistency.
Keep it overnight or minimum 6 hours for fermentation.
Grease the idli plates with some cooking oil and fill it with the fermented batter.
Steam it for 8-10 minutes and serve it hot with some sambar or chutney.