SEAR: Heat the pressure cooker on high (use sauté button for Instant Pot), when hot, add the oil along with the carrots, onions, celery, and garlic and allow the oil to just brown the outside of the veggies for 1 minute. Remove the veggies to a plate.
MORE FLAVOR: Add the whole chicken (or pieces) to the pot and allow the skin to brown on both sides for a total of 4 minutes.
FILL: Add the veggies back into the instant pot along with the peppercorns, nutritional yeast, salt, parsley, and thyme. Pour in cold water till it reaches the 10 cup line.
PRESSURE COOK: Seal the valve. Lock the lid, cook on manual, high pressure, for 60 minutes. It'll take around 20 minutes for the pressure to build up before it actually starts the cooking process.
STRAIN: When done, move the valve to the 'venting' position to do a quick release, but I strongly suggest a natural pressure release for maximum flavor. Allow the broth to cool a bit before removing the chicken and veggies pieces.
STORE: If using a whole chicken you can shred it and use immediately or freeze till ready to use. Once the broth cools a bit, strain it into freezer safe containers (if freezing). You can refrigerate the broth for up to 5 days and freeze for up to 2 months.