Place all the ingredients in a
large saucepan and bring slowly to just below boiling point. Simmer for 20 minutes, removing
any scum from the surface. Strain the stock through a
muslin-lined sieve and leave to cool before refrigerating.
Note - When purchasing the trimmings for this
stock, avoid buying the skin and bones of oily fish. It is very
important that the stock does not boil as it will become very cloudy.