In the same Kadhai. Add little mustard oil. Add chopped onion. Fry for few minutes. Then add 1" ginger, 2 green chilli and mustard seed paste, 1/2 tsp turmeric powder, 1 tsp red chilli powder and salt. Saute it for a few minutes. Till the raw smell of masala goes off.Mix....well. Add 1 cup water. Stir it well for 1 minute. Add fried fish. Cover and cook for 3 minutes. Once it done. Open the lid. Add coriander leaves. Transfer to a serving plate