Chop vegetables: Wash and roughly chop the leek (using the white and light green parts), onion, carrots, and celery.

Combine ingredients: Place the chicken carcass, chopped vegetables, smashed garlic, peppercorns, bay leaves, herbs, and apple cider vinegar (if using) into a large stockpot. Cover everything with cold water.

Simmer the stock: Bring the mixture to a low boil over medium-high heat. Skim off any foam that rises to the surface with a large spoon. Reduce the heat to low and simmer gently for 2 to 4 hours, uncovered. The longer the simmer, the more flavorful the stock will be.

Strain and cool: Remove the large solids with a slotted spoon. Carefully pour the remaining liquid through a fine-mesh strainer or a colander lined with cheesecloth into a large bowl. Let the stock cool completely.

Refrigerate and store: Once cooled, transfer the stock to airtight containers. Refrigerate for up to 4 days, or freeze for up to 3 months. For less fat, chill the stock overnight and scrape the solidified fat off the top before storing.

For instant pot

Turn Instant Pot to saute and brown the chicken carcass for 3-5 minutes per side.

Add remaining ingredients.

Turn the Instant Pot to cook at high pressure for 45 minutes. It will take about 20 minutes to come to pressure.

After cook time, let the pressure cooker release naturally (takes about 30 minutes).

Pour the Instant Pot contents into a fine mesh strainer over a large bowl. Discard bones and vegetables.

Use immediately or let cool completely and store in the fridge for 3-4 days. Freeze for up to 6 months.