1 tbsp. olive oil
2 medium onions, halved
3 large carrots, cut into 1-inch pieces
3 stalks celery, cut into 1-inch pieces
1 chicken carcass plus any extra chicken scraps
3-4 quarts of water
1 teaspoon black peppercorns
1 tablespoon kosher salt
Few sprigs of fresh thyme and rosemary
Heat the olive oil in a large stock pot (about 5-6 quarts) over medium-high heat. Add the onions, carrots, and celery to the pot and cook, stirring occasionally, until the vegetables begin to brown slightly, about 5-10 minutes. Add the chicken carcass to the pot. Add enough water to nearly fill the pot. Stir in the peppercorns, salt and herbs. Increase the heat to bring the mixture to a boil. Reduce the heat to a very low simmer and let simmer 4-5 hours. Let cool slightly.
Pour the stock through a fine mesh strainer into a large pitcher or bowl to remove the solids. Cover and chill in the refrigerator. A layer of fat will form on the surface, which can be skimmed off and discarded. Transfer to storage containers and freeze until ready to use.