Blend the coriander, chilli, garlic, ginger, cumin seeds and half the oil until chopped finely.
Combine the coriander mixture with the coconut, crushed pistachio nuts and oil in small bowl; mix well. Score each fish three times both sides. Brush the halibut with melted butter, leave to cool and press the coconut pistachio mixture onto the fish. Pan-fry the fish skin side up only for a few minutes and finish in the oven for approximately 8 minutes at 200 degrees celsius.
Serve with lemon wedges, steamed long-grain white rice and stir-fried bok choy, if desired.