Preheat your oven to 400F. While the oven is warming up, place your beef bones in a single layer on a baking tray and drizzle olive oil.
Roast the beef bones for a total of 1 hour, I recommend 30 minutes on each side. This is an entirely optional step, but I think it adds some extra flavor and adds a nice dark color to the broth. While the bones are roasting, prepare your vegetables by cutting it up in chunks.
Once the bones are ready, combine all the ingredients in a slow cooker or a large stockpot. Cover with water so everything is immersed, and add 2 tablespoons of apple cider vinegar for some extra flavor.
Put on the lid and turn the stockpot to high setting. Once it reaches a rapid simmer, lower the setting to low, and simmer for 12-24 hours. Check occasionally to top off with water as needed.
After it’s done simmering, strain the vegetables and bones. Most of the nutrients will have been extracted, so you can discard the ingredients. Pour the broth into mason jars and store in the fridge.
When you’re ready to drink, just skim off any fat that has solidified on the top. Reheat it and drink it straight, or as a base for your soup.