Line a bamboo steamer with a parchment paper.
To prepare Thai marinade, combine galangal, lemongrass. garlic, bird eye chillies, salt, crushed peppercorns and oil in a bowl and mix. Add lemon juice and mix well. Add 4 fish pieces, rub well and set aside.
To prepare Italian marinade, combine 1 tbsp olive oil, dried mixed herbs, crushed peppercorns, salt, torn rosemary sprigs and torn basil leaves in a bowl and mix. Add lemon juice and mix. Add garlic and mix. Add 4 fish pieces, rub well and set aside.
To prepare Parsi marinade, grind together coconut, garlic, green chilli, cumin seeds, torn coriander sprigs, lemon juice and salt alongwith some water to make a fine paste.
Place remaining 4 fish pieces on the worktop. Put the ground marinade on it and rub well.
To soften banana leaves, heat it directly on the gas for few seconds or till shiny and place on the worktop.
Wrap the marinated fish pieces individually on each banana leaf and seal by tying a thread around.
Heat some water in a non-stick pan and bring to boil.
Place the fish parcels in the lined bamboo steamer. Place the steamer in hot water and steam for 10-15 minutes.
Transfer the steamer on the worktop and remove the parcels on the worktop and unwrap them