Heat the oil in the cooker until very hot, then add the beef and the bones —as much as comfortably fits at one time— and cook until well browned. Repeat with the remaining beef and bones.
Drain off any excess fat.
Add the remaining ingredients to the cooker, close the lid, and bring to pressure. Cook for 60 minutes on High pressure (or 1 hour 45 minutes on Low pressure).
Reduce the pressure, remove the lid, and strain, pressing with the back of a wooden spoon to extract as much liquid as possible.
Refrigerate overnight and remove the fat from the surface the next morning. Use as you would any stock.