Grind together coconut, green chilli and ginger to a smooth paste with 1/2 -1 tbsp water.
Whisk the yoghurt well. Add the coconut paste to the whisked yogurt and combine.
Add finely chopped onion, salt and sugar to this mix.
Add chopped coriander leaves to this and mix well.
Add mini idlis to this and combine everything together.
Heat oil in a pan and fry the sliced small onion, dry red chilli, ginger and curry leaves till the onion turns golden brown. Add this to the idli mix. Refrigerate for 1-2 hours. Serve chilled
Just before serving, garnish with kara boondi/sev and chopped coriander leaves. If you add the kara boondi and sev and refrigerate, it might turn soggy.
Notes
You can also use regular size idlis to make this. Just cut it into small pieces and follow the recipe. If you dont have mini idli tins, but still want to make it, here you go... steam idli batter in a cake tin. Once it is done, cool it and cut out mini idli's using a round cookie cutter or bottle cap. You can also use grated carrots to make it extra healthy. Just add it along with chopped onion. If you feel that the idli's have become hard, add around 1/4 cup of milk and keep for 5 mins, before serving. It will soften the idlis. You can use Kara Boondi or Kerala Mixture or any fried savory snack as a garnish.