Grind the rice finely. Soak the sago. Grind the green chillies and salt into a paste. In a large saucepan bring the water to boil. Add sago and curd and boil it till sago becomes transparent. Gradually add the rice flour, stirring constantly. COok for 10-15 minutes till done. Cover and leave for 5 minutes on slow flame. When done, mix lemon juice, chilli paste and salt and mix well. The mixture should be ground in a wet grinder to avoid lumps. Fill the murukku mould with the prepared dough and press on a sheet. Allow to dry in the sun for 2 days. Dry for one more day and store in tins. These have to be fried in hot oil till crisp.