Thassos has a good supply of honest tavernas, most of them near the water. Fish is the thing to order — grilled octopus, sea bream, red mullet — along with whatever the boat brought in that morning. The island produces its own white wine and an excellent thyme honey; both appear on almost every table.
Thassos Town has the widest choice, but some of the better food is found in the smaller coastal villages. Avoid anything with an English-language menu displayed prominently outside. The further you walk from the ferry port, the better the value.