Soak the rice and the dal separately, for about 5-8 hours. Grind the rice using a blender or food processor in batches with sufficient water until it is a smooth paste. Start with a small amount of water and add until the paste is thin enough to flow smoothly.
Now grind the dal in two batches. The dal needs to be ground while slowly adding more water from the top of the blender. (When ground, the dal has the tendency to fluff up, this tendency must be encouraged by adding only a little water at a time while stirring and continuing to grind. The dal should double in quantity after grinding, while the quantity of rice would have remained unchanged.) Now mix both the pastes with the salt in a dish that is at least a third bigger in size, allowing space for the dough to rise. Leave for about 8 hours in a dark warm place like an oven that has been heated to 200 degrees and turned off.
Use a heavy cast-iron griddle (a flat non-stick pan will do). Heat the griddle/pan until a few drops of water dropped on the surface sizzles. Take a deep ladle full of dough and drop the dough in the middle of the pan, quickly swirl the dough away from the middle until it is spread evenly in a circle around the pan. You must do this quickly because once the dough cooks, it is difficult to spread. Take a teaspoon full of oil and spread it around the edge of the dosai. Wait a minute or so, until you see the edges browning and insert a flat ladle that has sharp edges under and all around the dosai, until it is released completely. After releasing the dosai, flip it around on the other side and put another teaspoon of oil around the edges. Wait a minute or two until it is cooked and remove from the pan.
Before making the next one, use a small piece of paper kitchen towel and rub any excess oil off the pan. Dosas can be stuffed with a spicy potato stuffing or eaten plain with coconut chutney and sambhar.
From the Dinner Co-op