Preheat oven to 450 degrees. Place chicken bones in single layer in one or two roasting pans. Place in oven and roast 40 to 60 minutes until well browned. Remove from oven and place bones in large stockpot. Add onion, celery, carrots and garlic to one roasting pan. Stir to coat with chicken juices, and return to oven. Roast 20 minutes until beginning to caramelize. Stir in tomato paste and roast another 15 minutes. Remove from oven and remove vegetables to stockpot. Add wine to roasting pan and scrape up browned bits. placing over a burner if necessary to loosen caramelized bits. Pour into stockpot. If you used 2 roasting pans for the bones, pour a little water or wine into the second one and scrape up caramelized juices; add to stockpot. Add herbs and peppercorns to stockpot, along with the contents of your stock bag, if using, then add enough cold water to generously cover the contents by 3 inches or so. Bring to a simmer over high heat then skim foam, reduce heat to very low, and simmer very gently 4 to 6 hours until all cartilage has melted off the bones. Strain through a coarse strainer into a large metal bowl, cool at room temperature 2 hours, then place in fridge uncovered until chilled thoroughly, then cover. Will keep for 2 days until made into soup or reduced and frozen as above to have on hand. Strain through fine mesh strainer before using or freezing.