Cover the brown rice with water in a microwave-safe bowl and nuke it for five minutes.
Allow the rice to sit in the hot water for another half an hour.
Now add the rice to the remaining ingredients, along with the water. Add more water to cover the lentils and rice. Allow them to soak for at least 5 hours and more if you have the time. Drain.
Blend the rice-dal mixture, in several batches, adding enough water to make a smooth batter that's runny enough to spread into a crepe, but thick enough to coat the back of a spoon. At this point, you can leave the batter to ferment overnight, which helps beneficial probiotic bacteria in the batter grow. You can also make the dosas rightaway.
To make dosas, heat a cast-iron or non-stick griddle. The griddle should be hot enough that when you sprinkle a few drops of water on it, they sizzle and evaporate.
Using a ladle with a rounded bottom, pour some batter into the center of the griddle and, in a quick but smooth motion, spread outward in circles. Don't be afraid if you make holes: just add a small drop of batter to patch it. If your dosa does not spread smoothly, it's possible your ladle is hot. Turn off or lower the heat, and try again.
Pour a few drops of oil around the dosa's edges to help it crisp up. Once the underside is golden brown, loosen the dosa gently from the skillet and flip over. If your griddle was hot enough to begin with, this step will be very, very easy.
Cook the other side for a few seconds, giving more time if your dosa is thicker. Serve hot with some sambar or chutney or both.
To make the chutney, just give all the ingredients a whir in the blender until the cilantro is completely broken down. Check salt and serve with the dosas.