For the coconut sauce, heat the butter in a frying pan over a medium heat. Add the onion, ginger and lime zest and fry for 4-5 minutes, until softened.
Add the wine and boil for 2-3 minutes, until the liquid has reduced by half.
Add the coconut milk and simmer for 5-6 minutes. Stir in the basil leaves.
For the fish, heat the olive oil in a separate frying pan over a medium heat. Fry the trout for 2-3 minutes on each side, until the skin is crisp and the fish is cooked through.
To serve, place a ladleful of coconut sauce onto a serving plate, and place the trout on top.