Add leftover bones into pressure cooker, plus enough water to just cover the bones. You don’t need to thaw the bones before cooking. But you do want use a pair of tongs to re-arrange them so you won’t need to use too much water to cover them. It will save you tons of time when reducing the broth later.
Add green onions and ginger.
Cover and make sure the high pressure valve is sealed. Cook at high pressure for 1 hour. Let pressure release naturally.
Discard the bones and aromatics. Drain the liquid with a strainer. If you want your soup clear, use an oil separator to remove the fat. I always keep the fat because it adds a very rich flavor to my soup.
For easy storage, I always reduce the broth beforehand. Transfer the drained broth into a pot. Cook over high heat until reduced to half (about 4 cups).
To store the broth, let it cool first. To cool the broth faster, place the pot into an ice bath and stir the soup constantly with a spatula. Soup can be cooled in a few minutes this way.
Transfer the portion of broth that you intend to use soon to an airtight container, and store it in the fridge for 3 to 5 days.
Transfer the rest of the broth to large silicone ice cube trays and put them into the freezer. When the broth cubes are frozen, you can transfer them into a large freezer bag to save space. If you’re planning to store them in the ice cube tray, place the tray into a freezer bag and seal it. Store it in the freezer for up to 3 months.
When you use the reduced bone broth, don’t forget to dilute it with water (according to taste), because it is very rich and concentrated.