Pressure cook for one whistle on high flame and then leave for 15 minutes on simmer. Switch off and allow to cool completely.
Once cool, drain to separate the stock.
Keep stored in sterilized glass bottles in the fridge and use within two weeks.
Notes
The stock this way is quite thick. When using, you can add water as required to thin it. You can add more spices if you want. Adding some cloves, paprika, parsley, etc. will add more flavor.