Take Urad, idly rice, regular rice, fenugreek seeds & poha. Mix all these in a bowl, wash 3-4 times and soak in enough water for 3-4 hrs.

Grind this mixture to fine batter of pouring consistency. If you are using mixer then add chilled water while grinding.
Keep this batter in warm place for 12-14 hrs. Or overnight for fermentation. It doubles up when fermented properly.

Before making dosa, add little water and salt. Mix well. Carry a piping bag pour the batter on it.

Fold the dosa, serve with sambar.