I was in Hat Yai from 3-14 to 3-24. It was boring as hell. I didn't even shot once.
The open air restaurants I found ok are : Song Charoen Hatyai, ร้านอาหารญี่ปุ่นมะลิจัง Marichan Japanese,
Cook Chai Dim Sum ThungSao, Hong Thong Noodle and Chingzin Vegetarian restaurant.
Kim Yong Market has ready to eat flavored shredded squid for 550B /kg. Tasted the same as the squid at JB's KSL CITY Mall.
See the map for the only place I found after 6pm. I walked the soi and an old man said to me “ying“