I first tasted this dish at a Parsee celebration where individual banana leaf packages of delicately steamed fish were unwrapped at the table. Serve with basmati rice.
Put the fish fillets in a shallow dish and squeeze over the juice from one of the limes.
Put the coconut in a food processor and add the green chillies, fresh coriander, fresh mint, cumin, sugar, and the remaining lime juice. Process the chutney until smooth adding a splash of water, if needed.
Tear off four large squares of foil (or use banana leaves