Put all the ingredients into a large stock pot or your biggest saucepan, and top up with 2 litres water. Add more water to cover all the ingredients if needed.

Bring to a simmer over a high heat, skimming off any foam that appears on top of the liquid with a spoon. Reduce to a medium heat, then simmer, half covered, for 3 hrs – the stock will have reduced and concentrated its flavours. Or, if you prefer a lighter stock, cover fully while simmering.

Turn off the heat and leave to cool for a few minutes, then carefully strain into a container or bowl to cool completely. Will keep in the fridge for a week and for three months in the freezer.