Finely chop the onion and raw mango and keep them aside.
In a mortar and pestle, add 1 green chili, ½ tsp cumin seeds, a pinch of salt, and 4 tbsp salted peanuts. Coarsely crush the mixture.
In a mixing bowl, add 1 cup chopped onion and ¾ cup chopped raw mango. Add salt, 1 tbsp jaggery, the coarsely crushed peanut mixture, coriander leaves, and 1 tbsp raita masala. Mix well.
In a pan, heat 2 tbsp oil. Add ½ tsp cumin seeds, curry leaves, and a pinch of red chili powder. Mix well and pour the tempering over the kachumber.
Serve kanda-keri kachumber with paratha, roti, or rice.