1 Remove the gills and eyes from the fish, or have your fish store do it. Cut the heads and bones across into 4-inch pieces. Put them in a shallow pan and cover with cold water. Let stand for 1 hour, changing the water twice. Drain.

2 Heat the oil in a large pot over medium heat. Add the onion, fennel, leek, peppercorns, salt, parsley, and bay leaf. Turn the heat to medium-low and cook until the vegetables are softened but not browned, about 4 minutes.

3 Add the fish bones and cook, stirring from time to time, until the bones and any flesh around the bones turn from translucent to white, about 12 minutes.

4 Add the wine and water and bring to a boil. Boil for 10 minutes, skimming off the foam as it rises to the top. Remove from the heat and let rest for 10 minutes.

5.Strain the fumet through a fine-mesh sieve, pressing firmly on the solids to extract as much of the flavorful liquid as possible. If you have more than 3 cups of fumet, place the liquid in a clean saucepan and boil until reduced to 3 cups. Store, tightly covered, in the refrigerator for up to 3 days, or in the freezer for up to 2 months.