Combine all of the ingredients in a stockpot and bring to a boil over high heat. Reduce the heat and simmer for 20 minutes, skimming frequently. Cover partially, leaving only a small opening, and simmer over low heat for 2 1/2 hours.
Strain the stock into a large bowl, pressing on the solids. Wipe out the stockpot, return the stock to it and boil until reduced to 2 quarts. Let cool slightly and refrigerate. Remove the solidified fat from the stock before using.
The stock can be refrigerated for 3 days or frozen up to 2 months.