Just back from the Lisbon coast; and returned very happily surprised both with the food and the wine- not to mention the porto!
a couple of standouts: in Barrio Alto, Alfaia (travessa da Quemaida), nice, chic restaurant with great sea food- some portuguese specialities. Octopus and dourade recommended, as well as the ice creams. In Alfama, Mammequer Bemmequer, which in spite being on the tourist route, was excellent: great sardines, nice salads -a difficult find in Lisboa- and fab bacalao com natas.Lunch WILL take three hours here, but order some Gazela vinho verde and enjoy the pace.
As every guide book will say; the pasteles de nata in Pasteleria Belem will floor you. Do not leave Lisboa without having one.
The highlight of the chowhound experience were the pastelerias- excellent pastries, everywhere, with strong black coffe (bica); Recommended: Queijadas in Sintra (Pasteleria Paquita), toucinho do ceu (almond and cinnamon cake) and bolo de arroz. A good pasteleria en Barrio Alto is Pao de Canela.
Portugal also has excellent cheese and bread; which with some presunto (ham) and wine will make for a great lunch.
While in Lisbon, I would also recommend trying some of the specialties of Portugal's former African colonies. Two stand-outs are Restaurante São Cristóvão and Cartuxinha, both on Rua de São Cristóvão. They are both located in the Mouraria neighborhood, itself a treasure-trove of colonial Portuguese cuisines.