Preheat oven to 200°C.
Mix turmeric with some lime juice and rub inside and outside the mackerel.
Sauté prawns, garlic, ginger, chilli, and curry leaves in oil until garlic changes colour.
Add cumin seeds, then sauté onions until soft.
Stir in cumin and coriander powders blended with 100ml water.
Season with salt, fresh coriander, and remaining lime juice before cooling.
Stuff the mackerel and secure with string or wrap in greased foil.
Bake on a greased tray at 200°C for 7 minutes per side, or 12 minutes per side if using foil.
Boil potatoes until just tender, then cool and slice thinly.
Fry potato slices in oil over medium heat until lightly coloured.
Flip potatoes, sprinkle with cumin seeds, and fry for 15 seconds on each side.
Sear the beef tomatoes in the same pan.
Serve the fish with potatoes, tomatoes, and seasonal leaves.