Put all of the ingredients in a heavy 2-gallon stockpot. Add 1 gallon of water, which should cover the ingredients by 1 inch, and bring to a boil over high heat. Reduce the heat to medium-low and simmer, uncovered, for 2 hours, skimming the surface occasionally with a slotted spoon to remove any foam that rises to the surface.
Remove the pot from the heat and strain the stock through a fine-mesh sieve into a clean container. Let cool, then cover the stock and refrigerate in an airtight container for up to 3 days or freeze for up to 2 months.
Makes 3 quarts