Heat 1/2 sp oil in a pan add semiya and fry till light brown then remove from the pan to a plate. In the same pan stir suji with 1/2 sp of oil until a nice aroma comes out then add it to roasted semiya and allow it to cool.
Take a bowl add yogurt and whisk it well, then add fried semiya, suji and mix well, if needed add enough water & salt. Heat oil in a pan add popu ingredients and fry once done add chopped cashew nuts & stir, remove from the pan & add it to curd semiya mixture and mix well.
Keep the batter aside for 20 mins then add cooking soda, if required add a little water and mix properly, grease the idly moulds with oil. Fill the batter into the moulds and cook in pressure cooker or steamer for 10-12 mins or until the idlis are done.
Remove the idly plates from heat and allow to cool, now semiya suji idlis are ready to serve, serve hot with any chutney.