Schrebergarten

This is one of the best places in Mainz for very tasty and fresh food. They offer Kumpir (which are stuffed potatoes), the vegan version of which is filled with walnut oil and then topped with a variety of ingredients. I absolutely recommend their 'Veganistan' potato, topped with red cabbage, carrots, mango-curry sauce and walnuts. Also some of their non-vegan potatoes can easily be made vegan. They also have nice vegan soups and vegan cookies for dessert.

If you are not so hungry, think about sharing a potato, they a huge!

A very pleasant spot, near the train station and not far from the tourist areas. Inexpensive. One topped baked potato is an ample dinner by European standards. As of this writing, it's all vegetarian with vegan options. The topping quantity is reasonable, so it's not all just potato. Nice outdoor seating, and adjacent to a small park with other little restaurants, bars, ice cream shops, etc. nearby if you want to make a picnic out of it.

Schrebergarten is a small restaurant in Mainz' town centre.
They serve filled potatoes called Kumpir (a turkish tradition), salads, homemade lemonade and soups.
The menu is really small but to my mind, this is positive and represents that the food they serve is fresh.
I tried the vegan kumpir version "veganistan" which was delicious and new to me.
Try this place, it's lovely :)

Good place for potatoheads and friends. Give this place a try-it is definitely worth it!
More updates after further testing oft the menue.