In a deep pot over medium heat, heat oil. Add onions and garlic and cook until softened.
Add chicken and cook, occasionally stirring, for about 5 to 7 minutes or until color changes. Lower heat, cover, and cook for about 15 to 20 minutes or until the chicken releases its juices.
Raise heat to high and add boiling water.
Add bay leaves, peppercorns, and salt.
Bring to a boil. Skim scum that accumulates on top.
Lower heat and return to simmer for another 10 to 15 minutes or until chicken is cooked through.
With a slotted spoon, remove chicken pieces. Allow to cool to touch and remove meat from bones. Shred the meat and set aside. Break bones to expose marrow and return to pot.
Continue to cook at barely a simmer, uncovered, for about 1 to 1 ½ hours or until liquid is reduced and concentrated. ASI
Using a cheesecloth, strain stock to remove bones and aromatics.