Bone broth, the slow method

• A 6-quart slow cooker with a low setting · The vessel
• Aromatics, salt, fat (full ingredient list ships with photography)

Method

1. 1

   Roast the bones first, 30 minutes at 220C

   2.5 kg of mixed bones, beef knuckles, marrow bones, and one or two oxtail pieces, on a tray, 30 minutes at 220°C / 425°F until deep brown. This is the single biggest flavour decision. Unroasted bones make a pale, weak broth. Roasted bones make a broth that tastes like a roast dinner.

2. 2

   Cold-water start, never boil

   Bones into the slow cooker, cover with cold filtered water (around 3 litres), add 2 tablespoons of apple cider vinegar and let sit for 30 minutes before turning the heat on. The acid pulls calcium and collagen out of the bone matrix. Cold-start prevents albumin scumming the surface.

3. 3

   Aromatics in the second hour, not at the start

   Onion (skin on, halved), 4 cloves of garlic (smashed, skin on), a leek green, two bay leaves, a small handful of black peppercorns. Add them after the broth has come up to temperature and skimmed once, adding aromatics to cold water means they over-extract and turn the broth slightly bitter by hour 18.

4. 4

   24 hours on low for beef, 12 for chicken

   Beef bones need the full 24 to break down properly. Chicken bones (whole carcass + a couple of feet if your butcher has them) only need 12. After 24 hours on a beef broth, you can crush the knuckle bones with the back of a spoon, that's the texture you're after.

5. 5

   No salt during the cook

   Salt during a 24-hour reduction concentrates beyond what you'll want at the end. Cook salt-free, salt at the mug. A pinch of Maldon and a squeeze of lemon when you sip, that's the seasoning. This is also why our broth is 240mg sodium per cup vs. 600mg+ in supermarket versions.

6. 6

   Strain twice, fine sieve, then cheesecloth

   Sieve the broth into a large bowl through a fine-mesh sieve first to catch the bones and aromatic debris. Then strain a second time through cheesecloth or a clean tea towel into your storage jars. Two strains is the difference between a cloudy broth and one you'd serve in a glass.

7. 7

   The fridge gel test

   Cool the broth to room temperature, transfer to wide-mouth jars, and refrigerate overnight. By morning, a properly extracted broth should jiggle when you shake the jar, that's collagen. If it's liquid, you didn't roast hot enough or didn't simmer long enough. Either way it's still drinkable; it's just less rich.

8. 8

   Skim the fat cap, don't discard it

   Beef tallow on top of a 24-hour broth is a useful cooking fat. Lift it off in one piece, store it in a small jar, it keeps for months in the fridge and roasts vegetables better than olive oil. Don't throw it away; it's free.

9. 9

   Sip a mug at the start of the day, not as a meal

   A cup of broth is 60 calories and 9g of protein. It's a bridge, not a meal. We drink it before breakfast on cycle days, with a pinch of salt, lemon, and parsley. Treat it as a hydration vehicle that happens to carry collagen, not as a dinner.

10. 10

    Freeze in 250ml portions

    Once the broth has gelled, ladle it into freezer-safe 250ml deli containers or silicone moulds. Freezes for 6 months. Defrost overnight in the fridge or pour straight into a hot pan from frozen. A 2.5kg bone batch yields 8-10 cups, enough for two weeks of daily sips.