In a large dutch oven pot, heat the oil over medium high heat until the fat is shimmering hot.
4 tablespoon olive oil
Pat the chicken thighs' skin dry with a paper towel, then season generously with salt on both sides. Place the thighs skin-side down in the hot oil and sear for 3-4 minutes, until the skin is crispy and golden brown.
4 chicken thighs, kosher salt and pepper
Flip the chicken over and sear the meat for another 3-4 minutes, until there is a golden brown crust. Remove them from the pan and place onto a plate.
Turn the heat down to medium and add to the pot the quartered onion, celery, carrots, the halved garlic head, thyme sprigs, and bay leaves. Season with a teaspoon of kosher salt. Sear until the vegetables gain some color, for 3-5 minutes.
½ large yellow onion, 2 medium carrots, 2 celery ribs, 1 head of garlic, 3 sprigs fresh thyme, 2 bay leaves
Pour the cold water and the apple cider vinegar into the pot, then add the seared chicken thighs back into the pot.
10 cups cold water, Capful of apple cider vinegar
Let the broth come to a gently bubbling simmer. Cover with the lid and simmer for 90 minutes, stirring ocsasionally so nothing burns on the bottom.
After the 90 minutes are up, remove the chicken thighs with tongs to let cool in a bowl until cool enough to shred. Shred the chicken with clean hands or forks and discard the skin and bones.
Carefully strain the broth through a fine mesh strainer lined with paper towels into a large heat-safe bowl or measuring cup. If you’re saving the chicken fat for the next step, try to hold back the vegetables so the fat drips straight onto the paper towels. If not, go ahead and discard all the solids: veggies, herbs, and peppercorns.
Transfer the fat from the paper towels into a small container, if using.