Fill large stock pot with 8-10 cups of cold water, enough water to cover all of the ingredients completely.
Set your stovetop burner to a low heat and bring the liquid to a low simmer.
Allow to simmer for about 4 hours, partially covered, scraping the fat off the top of the stock with a slotted spoon at least once per hour.
Pour through a fine-mesh sieve or cheesecloth to strain of all impurities.
Allow stock to cool completely before storing.
Notes
You can certainly make this in the slow cooker, as well! Just add the ingredients and water to the crockpot, cover, and cook on low for 8 hours. I do this overnight. It's important that you strain the stock with a fine mesh sieve or cheesecloth before storing. You'll be surprised how many impurities and fats are removed!