Set pressure cooker to "sear", add oil, and butter, and press "start/stop". When hot and butter has melted, add leeks. Cook until starting to look translucent.
Add potatoes, stock, water, sea salt, and pepper.
Close and lock lid and set pressure cooker to "soup", adjust time to 3 minutes, and press "start/stop".
When done, quick release and make sure all pressure is released before opening lid.
Carefully open lid and check seasoning. Add salt and pepper, if needed. Add parsley and Swiss cheese.
