Prepare the chicken bones. If you are using a raw carcass, you can roast the bones at 190 degree for 10 mins to get a darker stock, before adding it to the pressure cooker. For left over chicken bones, add directly to pressure cooker.
Add the diced carrot and onion to the pot.
Fill pot with water till bones and vegetables are submerged.
Close the lid and pressure cook for 45 minutes.
Once done, release the steam carefully. With the lid off, allow the liquid to come to boil and reduce to preferred thickness. (If you are storing these as stock cubes, reduce further.)
Use a metal strainer to separate the broth from the bones/ veggies, and discard bones/veggies after.
Store in the fridge for up to 3 days, or up to 3 months in the freezer.