3 cups Texas long grain rice
1 cup Urad dal (polished)
2 tsp Salt
Grinding: Soak the rice and the dal separately, for about 5 hours (soaking longer won't hurt, I usually soak it in the morning, go off to work, and grind in the evening.)
Grind the rice with sufficient water until it is a smooth paste. (I use my osterizer and run it in 3 batches, the amount of water used to grind is somewhat crucial, using too much will make the result too watery, while using too little will make it hard to grind and too thick. I usually put in the rice and add water until it just reaches the brim of the rice, this will seem like too much, but it will work out fine once the rice is ground.
I then run the osterizer on MIX until the rice is broken and then run it on LIQUIDIZE until the rice starts to become a paste. If required, add just a little more water, perhaps a few tablespoons. Touch the paste between your fingers to feel the texture. It should be smooth).
Now grind the dal in two batches. (The amount of water here is not as tricky. Traditionally this would be ground in a stone grinder by hand. The dal needs to be ground while slowly adding more water from the top of the osterizer. 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. (Quite commonly, the dough runs over for me, so I put it in a larger dish than worry all night about overflowing dough).
Leave for about 8 hours in a dark warm place. I usually leave it in the oven overnight and occasionally turn the oven on for a minute or two, to keep the air inside the oven at a warm temperature.
The next morning, if you have done all this, the dough is ready to be transformed into dosas. Use a heavy cast-iron griddle (a flat non-stick pan will do, but sadly lacks the taste that comes from the iron pan).
Heat the pan until a few drops of water dropped on the pan sizzles away
Take a deep ladle full of dough and drop the dough in the middle of the pan, then with a deftness that comes with practice, 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, you cannot spread it and the result will be lumpy.
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 (Be warned that, using a well scrubbed pan won't let you release the dosai easily. To prevent this, you might want to rub a little oil onto the surface of the pan before spreading the dough.)
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.
(This whole procedure sounds tedious, but its not too hard after you've done it a few times. Incidentally I make dosa every week. The dough will keep in the refrigerator for a week or more. If the dough starts to get sour, cut small pieces some green chilis and onion and add to the dough before cooking it. This can be done even otherwise, for a different flavour and variety.)
Eating: Break a piece of the dosa and dip it into the dosa-molaga-podi or the samber and pop it into your mouth.