Use a large pressure cooker, 6 to 9 qt.
Place all the ingredients in the pressure cooker.
Add enough water to fill 2/3 of the pressure cooker.
Close and lock, and over high heat bring the cooker to full pressure (it takes about 10 minutes).
Reduce the heat to the lowest setting, just to maintain the pressure, and cook for 45 minutes.
Turn off the heat, use the release method, wait for steam to stop and open pressure cooker according to manufacturer's instructions.
Open the cooker carefully. Line a colander with a double layer of cheesecloth and strain the stock into a pot or bowl.