Marinate the fish with 1/2 tsp turmeric, 2 tsp garlic paste and salt as per taste. Keep aside in a cool place for half-hour.
To make the masala, add 1 tsp mustard seeds, 1/4 tsp black pepper, 1/2 tbsp cumin seeds, 1/2 inch ginger piece and 1 tsp garlic paste in a blender. Grind to form a spiced masala. You can also grind the spices in a mortar pestle. Now mix red chilli powder and panch phoran with this mixture.
In a pan, heat mustard oil. Gently place the marinated fish into the pan and shallow fry the fish from both sides. Once fried, take out the fish and place them on a plate.
In the same oil, add the spice mixture and fry it for two minutes. Now add tomato paste made using 2 tomatoes and mix well. Let the masala cook until the tomato masala leaves oil. This will take 8-10 minutes.
Now add 2 cups of water to the pan and bring to a boil. Cook the gravy for 4-5 minutes.
Now add the fried fish to the thin gravy along with chopped coriander leaves. Adjust the salt as per taste and cook it for 4-5 minutes more.
Lip-smacking Rohu Fish Curry is now ready to be served. Pair it up with Rice or