This recipe for brown chicken stock can be used as a base for many recipes, such as chef Harold Dieterle's Spicy Duck Meatballs with Mint Cavatelli (pictured) or chef Brad Farmerie's Moroccan Braised Lamb Shanks.
Preheat oven to 450 degrees. Divide chicken evenly between 2 rimmed baking sheets and roast until golden brown, 45 to 60 minutes. Add onion, carrots, tomatoes, and leek. Roast 30 minutes more, stirring occasionally. Transfer to a large stockpot.
Combine parsley, thyme, bay leaves, and peppercorns in a piece of cheesecloth. Tie with kitchen twine to enclose. Add to a 10-quart stockpot.
Place hot baking sheets over low heat. Add 1 cup water to each baking sheet, scraping up browned bits from the bottom of the baking sheets with a wooden spoon. Add liquid to stockpot. Add enough water to cover bones by 2 inches, 20 to 24 cups. Bring to just a boil over high heat, and reduce heat to a simmer. Cook, skimming as necessary, for 2 hours.
Strain through a sieve lined with damp cheesecloth. Let cool to room temperature. Transfer stock to refrigerator and let chill over night. Remove and discard solidified fat from top of stock. Transfer to an airtight container.
Refrigerate up to 3 days.
Freeze up to 2 months.