If you want vegan pierogi you must visit Najadacze. They are incredibly tasty. They also have amazing soup. Whatever the soup of the day happens to be, get it. I would also recommend the chow mein.
The only thing I don't recommend is Kofta. It tastes great when it's done well, but it has been hit and miss (often miss) for me.
This is a small restaurant tucked away just outside of Rynek (market square). If you're coming with a large group there won't be much room for you, but you might be able to make it work.Pros: pierogi, green smoothie, location
Cons: seating, inconsistent quality