Bone Broth

In a slow cooker add:

2 lbs beef bones (roasted 30 minutes in 350 degree oven)
2 carrots, large chop
2 celery stalks, large chop (leafy ones are fine)
1 medium onion, quartered
1 Tablespoon Kosher salt
1 teaspoon peppercorns
2 Tablespoons apple cider vinegar
3 quarts water

Let cook for 48 hours, replenishing water if needed.

Last 30 minutes add:
2 cloves garlic, minced
1/2 bunch parsley

Strain through fine mesh strainer.