Reformhaus Buchmüller is quite an enjoyable place for having lunch although it's not perfect. Out of the five dishes per day usually (only) one is vegan - that could be more for a health food shop. I also didn't have the impression the staff knew exactly what she was talking about. She told us the clear veggie soup surely had milk in it which obviously wasn't the case. Then she discovered royale in it so it wasn't vegan anyway. They also had falafel and hummus on the menu that day and I wonder why that wasn't vegan.
However, the food we finally got served tasted very good. More than half of the dish were different salads, the cooked part consisted of rice, boiled kohlrabi in tomato sauce. It was quite delicious and cost 6,50€ per plate.
There is a sitting area outside to the street and behind the shop in the green backyard as well as a few tables inside.
The shop is quite small and even for Austrian prices pretty expensive.
Cons: products in shop pricey, few vegan options, staff could be more friendly