Roast bones, onions, and garlic for at 425 degrees F. If all of the bones are raw, roast for 1 hour. If the bones have been previously cooked, roast for 30 minutes.
Place all ingredients in the Instant Pot, finishing with water up to the max fill line. Close the lid and venting valve and set pressure cook to high for 3 hours.
After stock has cooked for 3 hours, allow the pressure to naturally release completely before carefully opening the lid.
Pour stock through a strainer and discard of the bones and vegetables, and other bits.
Line a mesh strainer with cheesecloth and pour stock through 1-3 times until clear of particles.
Once stock has cooled, you’ll notice a thin layer of fat collecting and solidifying at the top. You can skim this off immediately or leave it as a protective layer until you are ready to use your stock.