Olomouc has a wide and interesting range of restaurants to offer. These are close to the workshop venue and thus possible choice for lunch: 

5-10 mins walk from workshop venue:

10-15 mins walk from workshop venue (near/at historical city centre):

http://www.hanackahospoda.com/

http://www.nepalirestaurant.cz/

http://www.moravskarestaurace.cz/

http://www.restauracedrapal.cz/

http://www.bar-planb.cz/

https://www.hostinec-moritz.cz/

And many more! A lot of restaurants have outside seating in the summer, which is nice especially the sun doesn’t set till past 9:30pm in June. And the city centre is just 10-15 mins walk from the workshop venue, and there are a lot of cafes with cakes, coffee and ice-cream. 

And if you like fresh fries, check out this place (you can smell the fries when you are still 50 metres away, only take- away though):

 https://faencyfries.cz/