Makes about 8 cups of broth

Ingredients:

4 pounds beef or chicken bones (if possible include some red marrow bones)
2 medium carrots, chopped
2 celery stalks, chopped
1 medium leek, trimmed and chopped
1 medium onion, sliced
2 garlic cloves, diced
2 bay leaves
2 tablespoons black pepper
1 tablespoon apple cider
1 tsp salt

Instructions:
Add bones and vegetables to a slow cooker. Season with bay leaves, black pepper, apple cider vinegar, and salt. Fill with water. Cook on low for 18 - 48 hours.

Strain broth with a strainer or through cheesecloth. Let cool. A layer of fat will usually gelatinize on the top, you do want to discard it before warming up because otherwise, that fat will disperse back into the broth when it's warmed.