Set the pressure cooker to "sear", add bones, and press "start/stop".
Sear the bones, stirring occasionally, until the bones are brown and caramelized.
Once seared, add the onion, carrots, celery, garlic, parsley, thyme, bay leaves, peppercorns, and water.
Close and lock lid. Set the pressure cooker to "soup", adjust the time to 30 minutes, and press "start/stop".
Once the pressure cooker is done, let it naturally release its pressure. When all pressure is released, do a quick release to make sure all pressure has been released before opening the lid.
Strain the stock through a fine mesh strainer or cheesecloth.