Heat 1 tbsp ghee in a non-stick pan. Add semolina and sauté, stirring, on low heat till it turns a light brown. Transfer it into a bowl and allow to cool.
Add yogurt and mix well. Chop coriander leaves and green chillies and add. Heat 2 tbsps ghee in a small pan and add mustard seeds. When they splutter, add crushed peppercorns.
Remove the pan from heat and add broken cashewnuts. Put the pan back on heat and sauté till the cashewnuts are golden. Switch off the heat and add curry leaves. Stir and add this tempering to the idli mixture and mix.
Add salt and water, little by little, to make an idli batter of dropping consistency. Rest the batter for 10 minutes. Grease the idli moulds. Heat water in a steamer. Add fruit salt to the batter and mix well. Pour the batter into the idli moulds and steam for 10 minutes. Unmould and serve hot with any chutney.