Take 1 cup of sooji in a blender jar. Grind it into a powder. Now add leftover rice in a grinder jar. Grind it again for 30 seconds.
Then add 1 cup curd. Grind it for few seconds. Now add ¾ cup water and grind to a smooth batter.
Transfer the batter to a bowl and let it rest for 10 minutes. Add salt and baking soda to the batter. Mix very well.
Heat a pan and keep the flame to a low. Take a ladle of the batter and gently spread the batter. If the pan becomes hot, sprinkle some water.
Drizzle some ghee on the sides and the center. Ghee helps the dosa to be crisp. Continue to cook till the base becomes nicely crisp.