Rinse husked and spilt black gram (urad dal) in water a few times.
Soak the lentils adding enough water with fenugreek seeds (methi dana), overnight or for 4 to 5 hours.
Preparing batter
Drain all the water and add the soaked ingredients into a wet grinder jar.
Add ¼ cup of water or as needed. Grind the lentils finely, till smooth. Add more water if required while grinding.
Pour the batter in a vessel. Add salt and mix well.
If the batter is too thick, you can add some more water. But don't make the dosa batter thin as it will be difficult spreading the batter on the tawa or skillet.
The batter should be of pouring consistency.
Making urad dal dosa
Heat a non-stick tawa or well seasoned heavy cast iron skillet. Now take a ladle full of batter. Keep heat to a low or medium-low.
Pour the batter and gently spread the batter starting from the center and moving towards outwards.
Cook the dosa on low to medium heat. Make the urad dal dosa, the way you would normally make dosa with oil or ghee.
When you see the batter cooked on top, drizzle some oil on the edges and center.
Cook till the dosa looks crisp and golden. Flip the dosa.
Cook till the other side is also done.
Serve Urad Dal Dosa hot with coconut chutney or sambar.
Notes
Use urad dal that is fresh and not aged or old.
You can also add some finely chopped onions, ginger, curry leaves, coriander leaves, green chillies, cumin seeds and crushed black pepper to make the dosa more flavorful.
Do not cook these dosas for a long time as they can become chewy.
These dosa are best served hot. Do not store them or serve after they have cooled as the loose their crispy texture and become dense and dry.