Preheat oven to 200°C (390°F). Heat 2 tablespoons of the oil in a large frying pan over high heat. Add the fish and cook for 1–2 minutes each side or until browned. Remove from the pan and keep warm. Add the remaining oil, onion and garlic to the pan and cook for 2–3 minutes or until softened. Add the flour and cook for 1 minute. Return fish to the pan with the tomatoes, horseradish, cream, and parsley and stir to combine. Toss the bread with the melted butter and place over the fish mixture. Bake for 25 minutes or until the bread is golden and crisp. Serves 4.