Cut the onion in half leaving the skin on. Onion skin will lend a yellow hue to the broth. Add the onion skin side down to a stock pot with the cooking oil and cook over medium heat until browned.
Smash the garlic cloves on the countertop, removing skin. Add to the stockpot and cook until fragrant, about 1 to 2 minutes.
Add chicken bones to the stock pot. Optional: cook bones until browned. Browning the bones will lend a nice color and flavor. If the bones have already been cooked, do not bother.
Add carrots, celery, bay leaves, peppercorn, salt, herbs, and other optional add-ins to the stock pot.
Cover ingredients by 4 inches of water, at least 1 gallon.
Add vinegar or other acid to stock pot.
Bring to a boil.
Reduce heat to low. Place a lid on the pot and allow it to simmer over a low flame for at least 4-6 hours.