Ingredients – Makes about 4 litres
100mL vegetable oil
2 brown onions, peeled and sliced
8 white peppercorns
2kg fish bones and heads, well cleaned
Heat the vegetable oil in a large saucepan over medium-low heat. Add the onion and peppercorns, then allow the onion to sweat, frying gently without colouring for 5-10 minutes, until translucent.
Ensure the fish bones and heads are very clean, with no blood left on them and no gills attached. If the fish is not completely clean, the stock will be cloudy. Using a cleaver or large knife, roughly chop down the length of the fish backbones – this releases the natural gelatine into the stock, giving it more body.
Add the bones to the saucepan, cover with about 4 litres of cold water, and bring to the boil over medium-high heat. Reduce the heat to low and simmer gently for 30 minutes. If scum forms on the surface of the stock, skim it off immediately using a ladle.
Set the stock aside to cool for 30 minutes. Gently ladle it from the saucepan into a seive lined with muslin (cheesecloth) set over a bowl. Take care not to disturb the solids at the bottom of the pan and you will have a wonderfully clear stock. Discard the solids. Leave the stock to cool completely, then cover and refrigerate.
The stock will keep in an airtight container for 3 days, or in the freezer in portion sized container for 2-3 months.