Wash and soak rice in enough water for 10 hours.
Drain the water from the rice and add to a wet grinder or mixer. Add coconut, salt, red chillies, 3/4 tsp turmeric, onion and saunf to it. First, dry grind as fine as possible. Add water little by little to make a very thick and pliable dough.
Heat a kadai or pan. Add oil. Once hot, add onions and green chillies. Stir and fry till light golden.
Add salt, remaining turmeric, tomato and mix. Cook for a minute. Add prawns and coriander leaves and mix. Cook till the prawns are done.
Cool the prawns and mix it with the dough.
This roti needs to rolled with your hands like how we make akki roti.
Take a clean thick cloth. Wet it with water and place it on the kitchen slab. You can also use plastic sheets and greasing it is oil.
Take a small quantity of the dough (tennis ball size) and place it on the cloth. Pat it slowly and roll it out to an even roti using fingers to smoothen out the edges.
Heat a non stick tava. Take a piece of kitchen tissue. Dip it in oil and grease the tava with it.
Place the roti along with the cloth facing up. Slowly remove the cloth from one side.
Cook for few minutes and turn over. Cook both sides till done and looks crispy and roasted. Serve hot.