In the pressure cooker, saute the leeks and onion in the butter/oil until tender. Add potatoes and stock. Close cover securely; place pressure regulator on vent pipe.
Bring cooker to full pressure over high heat. Reduce heat to medium-high and cook for 5 minutes. (Pressure regulator should maintain a slow steady rocking motion; adjust heat if needed.)
Remove from the heat. Immediately cool according to manufacturer's directions until pressure is completely reduced. Uncover; cool soup slightly. In a blender, process soup in batches until smooth. return all to the pan. Add cream and parsley; heat through over medium-low heat (do not boil). Season with salt and pepper.
This recipe was fabulous! The only thing I changed was to add one tablespoon of 'herbs de Provance'. I topped each bowl with sour cream and chopped parsley. I used all organic items and used half and half. - 23 Oct 2016