Slash both sides of the trout and place in a shallow non-metallic dish. Combine the curry paste, ginger, mango chutney, 1 tbsp lemon juice, Greek yogurt and coriander, and spoon over the trout. Combine well until thoroughly coated. Cover and chill to marinade for 30 minutes.
Combine the yogurt, cucumber, garam masala and a splash of lemon juice in a bowl, and set to one side.
Place the fish on the grill and cook for 6 minutes. Carefully turn and cook for another 6 minutes until cooked through and lightly charred. Serve with the lemon wedges and raita.