Using sauté setting – Add oil, onions, carrots, and celery. Cook for about 5 minutes (until onions are translucent and carrots begin to soften).
Add vinegar, garlic, and bay leaf and continue cooking for 2 minutes, until vinegar has evaporated.
Add vegetable stock, salt, pepper, and potatoes, then mix well. Lock lid and cook for 7 minutes at high pressure.
Once time is complete, quick-release pressure then remove lid.
Remove bay leaf and mash well with a potato masher. (I don't recommend using any kind of blender because the soup will become super starchy.)
Ladle into a bowl and top with caramelized onions and/or fresh green onions.