In Portugal but specially Alentejo it's hard to find bad food! Almost every door will serve you well for a reasonably low price. Below are a list of the best restaurants on each town. We strongly recommend you try some of them if not all ;)
Beach club if opened. Food depends on the year
Troia onda azul (AKA Pereira)
You should really visit the first 3! You won't regret it.