1. Soak dried nethili dry fish in tap water for 15 mins and rinse well for 2 to 3 times. Remove the head part for all the fish and was again for two times and keep aside.
2. Chop onions and tomatoes finely and set ready to make thokku.
3. Heat a kadai, pour oil, once it heated well, add mustard, curry leaves and red chilies. Then add chopped onions, saute for 2 mins or till it turns transparent.
4. Then add tomatoes and sprinkle little salt over it. Cook for 5 mins or until it becomes pickle like consistency.Cook covered to reduce the time of cooking.
5. Then add the spice powders like red chili powder, coriander powder and cumin powder.
6. Stir for 1 min and add ¼ cup of water, after it starts boiling, add the washed dry anchovies.
7. Cook covered and medium flame for 7 mins. Stir occasionally to avoid sticking at the base.
8. Once it reaches thokku consistency, add chopped coriander leaves and turn off the flame.