Rinse the moong dal and rice separately and place each in its own bowl, adding the fenugreek to the dal bowl.
Fill each bowl with water, covering the dal and rice by about 1/2 inch and leave it on the countertop to soak overnight.
Drain the water off of both the dal and rice.
Add the soaked and drained dal and 1 cup of water to a blender and blend until very smooth.
Pour this mixture into a large mixing bowl.
Add the soaked and drained rice to the blender along with 1/2 cup of water and blend lightly leaving the mixture a bit grainy.
Pour this mixture into the bowl with the blended dal and stir well.
Place a towel over the bowl and leave on the countertop to ferment overnight or until the batter is bubbly and has a tart smell.
You can add a bit of salt at this point if you are using it.
The consistency should be like a runny pancake batter.
Preheat your well seasoned cast iron or carbon steel griddle or ceramic coated pan to medium high.
Pour a ladle of batter into the center of the pan and spread it out by spiraling your ladle gently over the surface from the center out to drag the batter outward, spreading it very thin.
Let it cook until the outer edge starts to brown. Don't try to flip it until the edge comes away from the pan easily with a spatula.
Flip and cook lightly on the other side.
You can lay the finished dosa on a plate, flat or gently roll it into a tube. (They will crack if you try to roll them once cooled)
Make only as many as you are going to eat for a meal and place the remaining batter in an airtight container in the fridge for up to a week or so until you are making them for another meal.
The cooked dosa doesn't save in the fridge well. They get very barky after sitting for a while.
Serve them with a spicy Indian chutney or with my Red Lentil Vegetable Soup.