Cut ginger into thin slices, then into thin strips. Heat stock in pan, add ginger and cook for 2 minutes. Remove ginger from stock and mix with spring onions. Put fish in stock and cook gently for 5 minutes, covered. Place fish onto serving plate and top with ginger and onions. Add soy and Asian seasoning to stock and bring to boil. Cook until reduced by half. Then turn off heat and spoon over fish.