Blanch stewing hen and pork bones in a pot of hot water to remove any impurities. Drain and rinse.
Bring water to a boil and place blanched ingredients inside. Add additional pork bones for a richer stock (see Chef’s note). Lower heat and leave to simmer for about 6 hours until reduced to about 3 litres (96fl oz / 12cups) stock after straining.
If not using immediately, leave stock to cool, then store in airtight containers or in covered ice cube trays for up to 3 weeks in the freezer.