The Food Gatherer's Note: Bone broths are all the rage ... why? They're extraordinarily healthy, taste good and are cheap to make. Any beef bones are good for this broth, but oxtail particularly. By roasting the bones first you get a richer deeper flavour. Try adding some greens and pulses to your broth for a wholesome hug of a winter soup. Emma :)
Turn the oven to it's highest heat, at least 200C, then put the beef bones, a quartered onion, some roughly chopped carrots and leek, plus a whole head of garlic halved through the middle onto a tray. Pour with a drizzle of olive oil and roast for 40 mins turning the contents of the tray halfway through. It should be lovely and brown.
Place in a stockpot or slow cooker and add roughly chopped celery, a couple of bay leaves and a few peppercorns. Add a generous pinch of salt, bring to the boil, then gently simmer on low for at least 12 hours.
Skim any scum as you go along then after cooking strain (in a fine sieve or muslin cloth, discard bones and veg and season the clear broth to taste.
Tip, the longer you cook it, the better it will taste.