After cleaning, fry the tilapia with a turmeric powder and salt paste in mustard oil, until brown.
Heat the pan and add 2 spoons mustard oil.
Add 1 tbsp black cumin & whole cumin seeds, stir it gently.
When you will get an aromatic smell, add 1/2 cup onion paste. Fry until onion is a brownish color. Now add 1/2 cup ginger garlic paste, 2 tbsp poppy seed paste, 1/2 tbsp turmeric powder, 1 tbsp chili powder, 1/2 tbsp mustard seed paste and add some water. Mix all the spices well and stir for few minutes.
Now add tomato paste and salt as per your taste. Stir for a minute.
Add one cup water for gravy. Now add the tilapia, one by one. Add 3-4 sliced green chili and 1 tsp mustard oil. Simmer on low heat for a minute. Open the cover and toss the fish. After simmering for a few minutes, serve hot!