try to take some time..after washing and cleaning the fish with turmeric, salt, oil, and lime juice...soak or marinate the fish pieces with some ginger n garlic paste, red chilli, salt, n turmeric powder for atleast an hour..in the mean while, grind the spring onion bunches, half onion, salt, little redchilli and ginger garlic paste(though we have added in marination, so add a little or else you could use only garlic cloves here)..this paste again goes into the marination for fish now the marination should sit atleast for 15mins..after this..switch on the stove, on a kadai or pan, add some oil, when it heat, add cumin and mustard seeds when they pop, add half left onion, let it to be well cooked, then add these fish and left over marinated paste too..after 10 mins if you want it gravy add some water (little) check the seasoning..when the fish is cooked..switch off the stove..but try to cook in slow flame to get the nice taste..so be patient..