How to Make It
In a pot, heat the oil. Add the fish bones and the leek, onion and fennel and cook over moderately high heat, stirring, until the vegetables are just tender, 15 minutes. Add the wine and bring to a boil. Cook over moderately high heat until reduced by half, 20 minutes. Add 8 cups of water and the parsley stems and simmer over moderate heat for 30 minutes. Strain the broth and season lightly with salt.
The stock can be frozen for up to 2 months.