Fumet de Poisson

Fish stock is simple and cheap to make, and essential for Normandy cooking. Any left over can be stored in two ways: either in conveniently sized pots in the freezer or else in the form of a fish glaze that can be kept for weeks in the refrigerator. To make fish glaze, strain the stock into a wide, shallow pan and boil it down to a tenth or even a twentieth of its original volume, depending on how concentrated it was in the first place. When the liquid is thick and syrupy, pour it into a li