We are going to be in LIsbon and Porto for 4 days each this May. Would love to hear about your favorite eating places. We are not fond of long 5 course meals but love good local food. Higher end or cheap eats, all welcome.
Thanks!

Another vote for Bom Jardim

In Lisbon, our favorite restaurant is Cervejaria Ramiro, recommended by the late Anthony Bourdain. The restaurant specializes in fresh seafood, and this is primarily what it serves. They might have a few meat dishes. We had enormous oysters, small clams in a garlic and oil sauce, huge rock crabs, giant prawns, and razor clams. The razor clams was the only dish we didn't care for.

We also liked Bom Jardim, recommended by thursdaysd and mms. The only dish we didn't like was the creamed spinach.

Had a delicious lunch at Restaurant Vela in Belem at the dock, overlooking the river.

You should also go to the Time Out Market, a huge market hall with tons of food stalls and small restaurants. We had a delicious meal at Monte Mar.

And another vote for Bon Jardin. Several people had recommended it, but when we got there we sort of looked at each other and said "Are they sure?" - didn't need to worry it was very good indeed. About 100 yards from Bom Jardin, along the narrow street, is a pastry shop that I think did the best Pasteis de Nata that I had on the trip.
Other restaurants I enjoyed in Lisbon were Farol de Santa Luiza (opposite the Miradour Santa Luiza in Alfama) and Chapito (up near the castle) - which had good food and a spectacular view.
Overall, we didn't have a great deal of luck at restaurants in Porto.

I was in Portugal in January. We ate very well. These are my top two in each city.

Lisbon: Cervejaria Ramiro, the seafood place Karen Woo just recommended. We were a table of 10, two of the people had steak sandwiches instead of seafood and they said they were also wonderful. The seafood though!! You can google Anthony Bourdain's TV episode about it.

Also in Lisbon, a good Fado Restaurant was Parreirinha de Alfama. The food was wonderful, Fado was excellent.

Porto: there is a smallish restaurant close to the Livrara Lello (the Harry Potter bookstore) called Trinkas. We had asked a local woman for her recommendation, and this was it. It was a good lunch place. I can highly recommend the cabbage soup and the bifana (pork) sandwich. We had a bifana in a recommended place in Lisbon (we were told they were the best in Lisbon) and they did not compare with the one we had at Trinkas.

Also in Porto, a tapas restaurant by the river, Jimao Tapas e Vinhoes. The owner/server lived in the US as a boy, he was great with his recommendations.

At Lisbon, I would definitly add "Adega das Gravatas" at Carnide if grilled octopus with olive oil and garlic is your thing (you will need a taxi, is not at the touristic centre; closed on mondays; it takes reservations and you should do it on weekends because locals line up at door).
More at center, cheap eats, "Zé dos Cornos" for pork ribs. No reservations and you should go early as locals line up for those ribs. Don't miss the chocolate mousse with brandy for dessert.