(Stuffing) Boil the potatoes and keep it aside. heat oil in a pan, crackle mustard seeds, jeera, curry leaves and hing. now add ginger garlic paste or chopped ginger - garlic and mix well.

Add chopped chillies and chopped onions and fry until they turn pinkish in color.
once the onions have changed the color, add turmeric and mix it properly.

Add chopped coriander leaves to it and mix properly. the masala will be hot so aloow them to cool little.
make small balls out of the mixture and flatten them as a patties and keep aside.

(Idli) In a large bowl, add 1 cup of roasted rava. using rava without roasting makes your idli slightly sticky, to that add 1 cup of curd or yoghurt. it is best to use slightly sour curd.

Add ¼ cup of water and mix it well. bring the batter to idli batter consistency by adding water if required.
keep the batter to soak for 30 minutes.

After 30 minutes add ½ tsp of fruit Eno (baking soda) and give a stir. you can now see the batter turning slightly frothy. do not mix more.

Now grease the glass for stuffed Idli. Now heat up the idli steamer by adding little water, and place a stand at the bottom.

Pour just a spoon of idli batter and place aloo masala roll in the center and pour a ladle full of batter over it.

Place this glass in the steamer over the stand and close the lid.

Steam stuffed idlis for 15 min till cooked properly. Cool down the glassed completely and unmold it. 

Cut slices of cylindrical rolls and serve immediately with coconut chutney or green chutney.