Preheat oven to 450 degrees F.

Arrange the pork bones on an aluminum lined baking sheet that has been brushed with a little oil.

Arrange the carrots, celery and onion on another aluminum lined baking sheet that has been brushed with a little oil.

Place both baking sheets in the oven and roast for 30 minutes.*

Place the pork bones and roasted veggies in the pot of the pressure cooker along with the garlic cloves, bay leaves and peppercorns.

Pour 8 cups of water over the mixture.

Place the lid on the unit and turn to locked position.

Turn the steam release valve to sealing.

Press the manual button and adjust the timer to 20 minutes.

When the unit is finished cooking, allow the steam to naturally release.

Remove the lid and use towels or pot holders to lift the inner pot out.

Pour the stock through a fine meshed sieve into a large pot.

Allow the lid to the pressure cooker to cool completely.

Place the bones and veggies back into the pot and wipe the bottom and sides very well.

Place the pot back into the unit and pour 8 cups of water in.

Repeat procedure for pressure cooking and straining the second mixture as described above.

Discard the bones and veggie mixture.

Once you have both batches of stock strained, allow it to cool and place in refrigerator overnight.

Skim any fat that has solidified off the top and discard.

Pour stock into canning jars and cover with lids.

Refrigerate or freeze.