Tim's Homemade Chicken Stock

Homemade Chicken Stock:

1 (3 1/2 to 4-pound) chicken, cut into pieces, or 4 pounds assorted chicken bones (wings, backs, necks)
2 ribs celery, roughly chopped
1 large carrot, roughly chopped
1 large yellow
onion, peeled and quartered
1 head garlic, cut in 1/2 horizontally
1 leek, well rinsed and roughly chopped, optional
3 bay leaves
2 sprigs fresh thyme
Parsley stems
1 teaspoon salt
1/2 teaspoon black peppercorns
4 quarts water

In a large stockpot, combine all the ingredients and bring to a gentle boil. Reduce the heat and simmer, uncovered, for 2 hours, skimming the surface occasionally to remove any foam that forms on the surface.
Remove from the heat and strain through a fine mesh strainer into a clean container. (If necessary, strain again.) Remove the meat from the bones and reserve for another use. Discard the bones and vegetables. Let the stock cool completely, and refrigerate overnight. Skim any fat that forms on the surface. Keep refrigerated in airtight containers until ready to use, up to 3 days, or freeze for up to 2 months.