I've always used bought stock, but this is just so good that I'll always keep my own stock in the freezer now. You can not beat it....superb!
Brown the chicken pieces (this adds to a deeper flavour)
Throw all of your vegetables in (no need to finely dice them)
Add liquid, pepper and bay leaves.
Pop lid on and bring to pressure and cook for 30 mins. Natural release (let the pressure come off on it's own)
Once pressure has dropped off, strain stock into large container and when cool, pop in fridge. Once it's cold, you can skim off any fats and then portion it up into containers for freezing. I use ice cube trays for some and snap lock bags for the larger stock.