For good flavour and nutrition, a beef marrow bone is a great addition to this bone broth. Make up the rest with chicken carcasses from roasts or lamb bones, which are also good for a rich flavour. Don’t forget the vinegar – the acid helps to extract the minerals and collagen from the bones.
Preheat the oven to 220C/200C Fan/Gas 7 and line a baking tray with baking paper.
Put the bones on the tray and roast for 30 minutes. Turn the bones, add the onion, carrot and garlic and roast for another 10–15 minutes, or until the bones are very browned and the vegetables are just browned.
Transfer the bones mixture to a very large pot or saucepan with a lid. Add the celery, bay leaves and peppercorns and cover with cold water – it should come about 5cm/2in above the contents of the pan. Drizzle in the vinegar.
Cover with a lid and bring to the boil, then turn the heat to a very low simmer. Cook, occasionally skimming off and discarding any foam and fat, for 8–12 hours. It tastes better the longer it simmers, but just check the water levels occasionally and top up if the bones are uncovered. If the majority of the bones are beef, chill the broth overnight in the fridge then continue cooking the next day for up to 24 hours in total. You can also make bone broth in a slow cooker on High for the same cooking time.
Strain the broth through a fine sieve, discarding the bones and vegetables, then leave to cool before chilling. The broth will last 5 days in the fridge and up to 6 months in the freezer.
The volume of broth you will make depends on how intensely flavoured you want it to be – the more you reduce the broth the more intense the flavour.