Soak the rice in a bowl of water for 6 - 8 hours.
Drain the rice, transfer to a blender or food processor, and process, gradually adding about 250ml / 8fl oz (1 cup) water to make a smooth batter.
Transfer to a bowl and season with salt. Set aside to ferment for 6-8 hours.
Stir in the grated coconut. The batter should be of a thin pouring consistency, so add a little more water, if necessary.
Heat a tawa, flat griddle or frying pan (skillet) over high heat until it sizzles when a few drops of waterare sprinkled on to it. Reduce the heat and smeara very thin film of oil evenly over the tawa.
Trickle a ladleful of the batter along the outer edges of the Tawa and continue trickling it inwards to form a wafer-thin, 15cm / 6 inch round adai. Fill any gapswith more batter.
Drizzle 1 teaspoon oil around the edges and fry for about 2 minutes, or until the base is golden, then lift the edges carefully and turn the adai over. Cook the other side for 2 minutes, or until crisp and golden.
Transfer to a plate and serve hot. Make the others in the same way.