Tenby area, South Wales
Nothing from personal experience, I'm afraid, nor in Tenby itself. But the Good Food Guide has a couple of places within a few minutes drive:-
Cors at Laugharne - www.the-cors.co.uk. Menu apparently changes daily which sounds fun.
and the Old Kings Arms, 13 Main Street, Pembroke, which seems to major on local produce/dishes (e.g. cockles with laverbread and grilled bacon).