Preheat oven to 180°C (355°F). Wrap the potatoes in aluminium foil and bake for 1 hour 30 minutes or until tender. Set aside.
Heat a large non-stick frying pan over high heat. Add the oil and onion and cook for 2–3 minutes or until browned, add the wine and cover with a tight-fitting lid. Reduce the heat to low and cook for 4–5 minutes or until the onion is tender. Add the cream and trout and cook for a further 2–3 minutes or until the trout is cooked through. Lightly crush the potatoes and spoon over the trout mixture. Serve with lemon wedges. Serves 4.