Soak grated potatoes in salted water for ten minutes. Drain and pat dry on a towel. Heat sufficient oil in a kadai.
Drop a handful of potatoes in hot oil and deep-fry till golden brown and crisp. Drain onto an absorbent paper. Deep-fry the remaining potatoes in the same way. Set aside to cool.
Fry one after the other cashewnuts, coconut slices, green chillies and curry leaves till light brown and crisp. Drain onto an absorbent paper and set aside to cool.
Combine all the fried ingredients in a big bowl. Add raisins, roasted cumin powder, garam masala powder, roasted fennel seeds, powdered sugar and rock salt. Mix well.
When completely cooled, store in an airtight container.