Ha Tinh is up to its ears in Cu Do, which you should definitely sample even if you're just passing through town.
Otherwise, eats are basic, but we had good luck with a nice bowl of chao (rice soup) and some oc nong (steamed sea snails) at Thuy Nha, on the west side of the main road just north of the Dai Bang Hotel. They also have nice, cold Huda beer.
Just a few doors to the north of that, Binh Nga offers up Be Thui (slow-roasted calf), and there's usually a carcass on a spit out in front of the shop. A plate that will satisfy 5 or 6 diners goes for 100,000 VND, and they have well-chilled Anchor beer on tap.
Binh Nga: 510 Cau Phu (main road), Ha Tinh. T: (039) 885 2160. Hours: 06:00 to 21:00.
Thuy Nha: Cau Phu (main road) just north of Binh Nga, Ha Tinh. T: (0958) 167 097. Hours: 07:00 to 23:00.