Heat oven to 400 degrees. Place chicken parts in a single layer in a large heavy roasting pan. Drizzle with oil and turn to coat. Roast, turning once and stirring of-ten for even browning, until beginning to brown, about 45 minutes. Remove from oven, add tomato paste, and stir to combine. Cook over medium heat about 30 seconds, then add carrots, celery, and onion, stirring well. Return to oven and roast until vegetables are browned and tender and bones are deeply browned, about 40 minutes.
Transfer bones and vegetables to large stockpot, then spoon off fat from roasting pan and discard. Set pan over two burners. Add wine or water and bring to a boil, scraping up any brown bits from bottom with wooden spoon. Boil until liquid is reduced by half, about 3 minutes. Pour everything into stockpot.
Add enough water (about 3 quarts) to cover chicken and vegetables by 1 inch. Bring to a boil, then reduce heat to gentle simmer. Add bay leaf and peppercorns; cook 1 1/2 to 2 1/2 hours, skimming surface frequently.
Carefully pour stock through fine sieve into large heatproof measuring cup, bowl, or another stockpot (do not press on solids); discard solids. Chill and store for up to 3 days in the refrigerator or up to 3 months in the freezer. Thaw completely in refrigerator before using.