Slash both sides of the trout and place in a shallow non-metallic dish. Combine the curry paste, ginger, mango chutney, lemon juice, Greek yogurt and coriander, and spoon over the trout. Combine well until thoroughly coated. Cover and chill to marinade for 30 minutes.
To make the yogurt raita, combine the low fat yogurt, cucumber, garam masala and lemon juice in a bowl, and set to one side.
To barbecue the fish, place the fish on the grill and cook for 6 minutes. Carefully turn and continue to cook for another 6 minutes or until cooked through and lightly charred.
Serve the fish with plenty of crisp green salad, some lemon wedges and the yogurt raita.