Bring the water to a boil in the pressure cooker while you trim and cut the vegetables. Add all the ingredients to the pot. (Do not go over the maximum fill line indicated by the manufacturer.) Lock the lid in place and bring to high pressure over high heat. Lower the heat just enough to maintain high pressure and cook for 10 minutes. Allow the pressure to come down naturally or use a quick-release method. Remove the lid, tilting it away from you to allow any excess steam to escape. 2. Let the stock cool slightly. Strain the stock, pressing the vegetables against the side of the strainer with a large spoon to extract all the liquid. Let cool completely, then refrigerate for up to 3 days or freeze for up to 3 months.