Hat Yai is one of the great food cities of Thailand, and the single best reason to come. The cooking sits at the crossroads of three traditions: southern Thai (fiery curries, generous use of turmeric, southern-style fried chicken), Sino-Thai Hokkien (dim sum, noodle soups, the dipping-sauce tradition), and Malay (rich curries, roti, satay). The proximity to Muslim Malaysia means halal food is everywhere, and the local Chinese population has kept dim sum culture alive in a way that has all but vanished further north in Thailand.
Two essentials: Hat Yai-style fried chicken (gai tod hat yai) — marinated in turmeric and southern spices, deep-fried, topped with crispy fried shallots — and dim sum, served from breakfast until late morning at dozens of dedicated shops.