Dosa (From Scratch!)

This recipe comes from Mark Bittman's How to Cook Everything Vegetarian.  He does not call it "dosa from scratch," but since everyone I know makes dosa from a box mix, I think this name sums it up better.  Now that I'm less incompetent at making pancakes, I'm hoping I can handle this.  If I can, we'll finally be able to have the long sought-after cheddar cheese and onion dosa that no respectable dosa shop will ever make on request.

Ingredients
1/2 cup white urad dal (dhuli urad)
2 cups basmati rice (you can also substitute brown basmati rice to make it whole grain and an earthier flavor and somewhat chewier texture)
2 to 3 tbs vegetable oil, as needed
Salt

Directions

1. Soak the dal and rice in separate bowls in water to cover for 4 to 6 hours, or overnight if you prefer.

2. Turn your oven to its lowest temperature.  Drain the dal and put it in a blender with a tbs or two of water.  Purée it to a smooth consistency, adding as little additional water as necessary, but enough to allow the machine to do its work. Transfer the purée to a large mixing bowl.

3. Drain the rice and add half of it to the blender (there's no need to clean between batches) with about 1/4 cup water. Again, purée (it won't become as smooth as the dal), adding as little additional water as possible. Repeat with the remaining rice. Add the puréed rice to the dal and stir the two together; the resulting mixture should have the texture of a thick pancake batter. Cover the bowl with plastic wrap, turn the oven off, and let the batter ferment overnight in the warmed oven.

4. Heat a large rectangular nonstick or cast-iron griddle over medium heat for a full minute before greasing it with a film of oil. Season the dosa batter with a large pinch of salt and stir to incorporate. Use a measuring cup or a ladle to pour 1/4 cup of batter into the center of the pan, then use the bottom of the measuring cup to spread the dough across the pan into a large oval shape not much more than 1/8 inch tick; don't worry if the thickness is inconsistent. (It's the same motion a pizza maker would make -- concentric circles with the bottom of the ladle -- to spread tomato sauce thinly and evenly across pizza dough.)

5. Tiny bubbles will form across the surface of the dough, and the bottom will crisp and turn a deep golden brown in 3 to 5 minute. Use a spatula to loosen the edges of the dosa, then roll it onto itself to make a cylinder and remove it from the griddle. Repeat with the remaining batter, greasing the griddle as necessary. Serve hot.