.... is probably Cafe Gopal.
This lovely, quaint little cafe serves a vegan buffet with an Indian theme. I found that half the buffet was traditional salads such as couscous and quinoa, and the other half was dishes such as lentil dal, chickpea curry, spinach curry and rice. They also had puppadoms and the most delicious crispy beetroot balls when I visited. You help yourself and pay by weight. I had a dish full of food and it came to 9 euros while my partner, who tends to eat more than me, had a plate piled high for 11 euros.
The lady, busy cooking in the kitchen as she worked, was really nice, helpful and spoke excellent English. Everything on the buffet was vegan when I visited which was great. She also had a counter absolutely full of cakes, with an entire shelf that were vegan. I was too stuffed to eat any pudding there and then but I got some cakes to take away which included an apple sponge drizzled with vanilla custard, a lemon and almond muffin and a fudgy chocolate, nut topped cake. They were all really yummy and only 1.50-3.50 euros each.
I would not hesitate to recommend Cafe Gopal as a great place to eat for anyone who is visiting Tampere.Pros: fresh and tasty buffet options, lovely atmosphere, fantastic cakes :)