Equipment
Ingredients
Bones
- 1000 g beef marrow bones, cut into thick segments
- 500 g beef knuckle bones, split
Aromatics
- 1 yellow onion, halved, skin left on
- 2 carrots, roughly chopped
- 2 celery ribs, roughly chopped
- 1 garlic, head halved crosswise
Seasonings & Liquids
- 30 ml apple cider vinegar
- 5 g black peppercorns, whole
- 2 bay leaves, dried
- 2500 ml cold water
- kosher salt
Nutrition (per serving)
Method
Preheat the oven to 200°C/400°F.
Spread the raw beef marrow and knuckle bones evenly on a baking sheet. Ensure you wash your hands thoroughly with soap after handling the raw meat to prevent cross-contamination. Roast the bones for 40 minutes until deeply caramelized.
Using tongs, transfer the hot roasted bones from the baking sheet into the slow cooker basin.
Pour a small splash of the cold water onto the warm baking sheet to loosen the fond. Scrape up the browned bits with a wooden spoon and pour this liquid over the bones in the slow cooker.
Add the halved onion, chopped carrots, celery, smashed garlic head, apple cider vinegar, black peppercorns, bay leaves, and the remainder of the cold water to the slow cooker, ensuring the bones are fully submerged.
Cover the slow cooker and set it to the low setting. Simmer undisturbed for 24 hours to fully extract the collagen and minerals. The slow cooker will easily maintain a food-safe liquid temperature well above the required 74°C/165°F for beef.
Carefully strain the hot broth through a fine mesh strainer into a large container, discarding all the spent bones, vegetables, and aromatics.
Cover and chill the broth in the refrigerator overnight. Once the fat has solidified into a thick white cap on the surface, scrape it off completely. Heat the clarified broth and season with kosher salt to taste before serving.
Chef's Notes
- Always start the slow cooker extraction with cold water. Cold water more effectively draws out the collagen and minerals from the bones as it slowly comes to a simmer, resulting in a superior texture and a much clearer liquid.
- Do not peel the onion; leaving the dry, golden skin on adds a beautiful rich amber color to the finished broth. Just ensure the exterior is washed thoroughly to remove dirt.
- The apple cider vinegar is essential but will not make the final broth taste sour. Its acidity slightly breaks down the hard bone matrix, maximizing the release of vital nutrients into your slow cooker.
- Save the solidified fat cap you scrape off after chilling. This purified beef tallow is an incredible cooking fat with an incredibly high smoke point, perfect for searing steaks or roasting potatoes.
- Do not aggressively salt the broth before simmering. As the water inevitably reduces over 24 hours, the salt will concentrate and you risk creating an overly saline base.
Storage
Refrigerator: 5 days — Store in airtight containers; the broth should become a firm gel when cold.
Freezer: 6 months — Leave headspace in the container to allow for expansion as the liquid freezes.
Reheating: Warm gently on the stovetop until fully liquified and steaming.
