Soaked separately overnight. Traditionally, stone grinders (huge mortars) and rolling pestles are used to grind the rice and the urad dal and motorized versions of those are now available at Indian elcetronic stores in D.C. A mixie or a blender cuts the grains into fine pieces, but does not "mash" them like the stone grinders do. So there is a good deal of difference taste when you use a blender. But still, it is not bad at all if you make sure that you grind the rice really fine. Cover the rice with water just 1/2 "above the rice line in the blender. Grind till Sssssmooth. Grind the dal separately, with water that barely covers it. Grind a long time (be patient!), stirring once in a while and grinding again. When the dal is ground very well, and small air bubbles appear once you stop running the blender, it is enough. Add more water if necessary. But this should be very thick. MIx the rice and the urad dal pastes, with 1/2 tsp salt. Add one tablespoon beaten yogurt, and mix well. Keep covered to let oit ferment fro at least 5 to 8 hrs or more. (Keep it close to a heater or in any warm place). Once it has risen, stir briefly, and keep it oin the fridge. You have the batter now. Grease a griddle with plain sesame oil or peanut oil if you care about max. flavor; if not use veg. oil. The heat should be medium or slightly higher. When hot (a few drops of water will sizzle gently and disappear), using a metal ladle, pour one ladleful over the griddle; with quick and even and gentle strokes, spread the batter out with the ladle as if you are drawing concentric circles on the batter. Do it either clockwise OR anticlockwise else you get lumps. It takes a few tries believe me, and some of us who are trained well in this mess up occasioanlly. drizzle oil around edges, and on top. Once the bottom is cooked, turn it over, and cook the top. Be careful when using your spatula (metal preferred) to take it out to flip it. This can be served with chilli-dal-spice powder and oil or ghee, coconut chutney, cilantro or mint chutney, onion chutney, or red garlic chutney, and/or saambar. (If you want their recipes, email me) This is standard breakfast or supper fare for us, growing up in the south.