Makes 8+ cups
Cut apart the leg quarters at the joints and leave the skin on. In a large skillet, heat the oil over medium heat and fry the chicken quarters with a bit of salt and rosemary until nice and brown. Remove those to a large stockpot and cover with water. Start heating the water on high.
Add a bit more oil to the pan and dump in the onions, garlic, carrots and leek or green onion. Here you want the flavorful tops, so don't throw out the leek tops if you're using that. Saute the veggies until they get a bit of color then dump them into the water with the chicken. Deglaze the pan with white wine and when all the browned bits (the "fond") have been scraped up, dump the resulting mixture into the pot.
Add the peppercorns along with the rest of the rosemary. Make sure there's enough water to cover everything by about an inch. By now it should be getting close to simmering. Bring it to a full boil, then cover it and let it simmer for 2 - 3 hours.
Every so often, skim the fat and other impurities from the surface. Using a fine-meshed sieve, drain the stock into a large bowl or container. Throw away all of the veggies -- trust me, they've given their all. Strip the meat from the bones and reserve for some other recipe needing boiled chicken, like chicken noodle soup or chicken salad.
Let the stock cool to room temperature then refrigerate overnight. The next morning, remove any fat that's solidified at the top. Pour into smaller (1 or 2 cup) containers and freeze, making sure to leave enough headroom.