2 to 3 raw chicken carcasses, halved, or 5 to 6 raw chicken backbones
2 leeks, white parts only, roughly chopped into 1-inch pieces
3 to 4 carrots, peeled and roughly chopped into 1-inch pieces
2 onions, peeled and quartered
1 6-oz. can tomato paste
1 bouquet garni (Recipe above.)
Kosher salt, to taste
Preheat the oven to 500 degrees or as hot as it will allow.
Place the raw chicken carcasses or backbones in a roasting pan and cook, tossing occasionally, 30 to 45 minutes, until very brown.
Add the leeks, carrots and onions and roast another 20 to 30 minutes until the vegetables start to brown. Carefully add all the roasted vegetables and bones to a large stockpot. Set aside.
Place the empty roasting pan on the stove over high heat and add the tomato paste and 1 or 2 splashes of water. Stir with a wooden spoon, scraping the bottom to release the fond. Add the tomato-fond mixture to the stockpot and fill with enough water to cover by 2 inches. Add the bouquet garni.
Place the stockpot over high heat and bring to a simmer, then reduce the heat to low so only one or two bubbles appear on the service every second. Simmer on low 6 to 8 hours, skimming any scum that rises to the surface several times during the first 30 minutes.
Remove the stock from the heat and strain it through a fine mesh sieve into another stockpot or large container. Discard the bones and vegetable scraps. Refrigerate the strained stock to cool completely and allow the fat to solidify on the surface. Skim the fat with a large spoon and discard it.
Return the stock to a simmer over medium heat and add salt to taste.
Strain the stock again through a fine mesh sieve lined with cheesecloth. Stock will keep, covered, in the refrigerator for 1 week and in the freezer for up to 6 months.