Mix yoghurt, lime juice, garlic, ginger, and spices in a bowl to create the marinade.
Coat trout fillets in the marinade and chill in the fridge for at least two hours or overnight.
Preheat the grill to its highest setting and blend melted butter with the remaining lime juice.
Grill trout fillets for 3 minutes and baste with the lime butter mixture.
Flip the fillets and grill for another 3 minutes, basting again halfway through.
Dissolve curry paste in boiling water and combine with beans, onion, lime juice, vinegar, oil, coriander, and chilli.
Divide salad onto plates, top with a trout fillet, and serve with naan bread.