Wash the rice and the Urad dal 2-3 times. Soak them separately for atleast 4 to 6 hours. Add Methi seeds to the Urad Dal while soaking.
After 6 hours, discard the water used for soaking and grind them separately using little water. Check the consistency below in the picture
Mix well with clean dry hands and keep it in a warm place for fermentation (8 to 10 hours / overnight).
Once the batter has risen, mix it gently with a clean dry spoon, add salt and some water to adjust consistency.
Always add few tblsp of water to the risen batter and do not directly steam it as it would lead to very dense idlis
Prepare the steamer and Grease idli moulds with oil.
Slowly fill the moulds with the batter and steam them for atleast 15 to 20 minutes on medium flame
Switch off the steamer, allow it to cool and then open the lid.
Demould the idlis once they have slightly cooled down else it would crack and break