01 - Place chicken bones in a large stockpot or Dutch oven; add onion, carrots, celery, garlic, and ginger.
02 - Pour in cold water to fully cover the ingredients; add bay leaves, black peppercorns, sea salt, and apple cider vinegar if using.
03 - Heat over medium-high until a gentle boil forms, then reduce to a very low simmer; skim foam and impurities from the surface during the first 30 minutes.
04 - Maintain an uncovered simmer for 4 hours, occasionally skimming and adding water as necessary to keep bones submerged.
05 - During the final 30 minutes of simmering, add fresh thyme and parsley for enhanced flavor if desired.
06 - Remove from heat and carefully strain the liquid through a fine-mesh sieve or cheesecloth into a large bowl, discarding all solids.
07 - Taste and adjust seasoning if needed; allow to cool, refrigerate, and skim any solidified fat before use.