In a large stockpot, combine all ingredients. Add enough water to cover by 2 inches. Bring to a boil. Reduce to a simmer and cook, for 3 hours.
Prepare an ice bath. Strain stock through a fine sieve into a large bowl set in the ice bath. Let stand, stirring occasionally, until room temperature. Transfer to airtight containers. Will keep, refrigerated, for up to 3 days, frozen, for up to 3 months.