On our recent trip to the iberian peninsula, we only had three days in Lisbon, so mostly explored the dining options near our hotel (The Riverside Hotel -- highly recommended) in the Alfama neighborhood.
We found excellent food, creative cooking, and welcoming and friendly staff.
We especially recommend, in the Alfama neighborhood, Taberna Do Vilarinho, at Rua das Canastras 8. The menu is all in Portuguese, as is the food, but the staff is helpful and understanding. Good wine selections, some unusual (to us) items like slices of slow-cooked pig's head, but we especially enjoyed the roasted lamb with sweet potato and the cod with scrambled egg and straw potatoes. This place alone would be worth a return trip to Lisbon.
We also enjoyed Taberna Moderna, just down the street from our hotel, a contemporary Portuguese restaurant set up in an old storefront, with a bar specializing in drinks made with gin in the back. We chose wines by the glass from a generous wine list, and enjoyed the scallop salad with goat cheese, rice with mushrooms and sausage, and poached eggs with eels and shrimp.
The surprise find of this trip was Da Prata 52, a pretty nondescript hole-in-the wall tapas place in Lisbon's main shopping district, recommended by someone at our hotel, that turned out to have delicious food (although the wine choices were limited). We really liked the green beans with hazelnut, the goat cheese rolls, the sauteed shrimp, and the diced sirloin.
Slightly further afield, we had lunch one day at Restaurante Raizes, across the street from the Museu Nacional de Arte Antiga, Again, we enjoyed a very helpful range of wines as well as their Salad of the Sea (green with scallops and shrimp,) the green beans with chorizo mayonnaise, and the sea bass with potatoes and ham, rounding out our lunch with their almond cake with sweet eggs for dessert.
We highly recommend a visit (or two or three) to the Vini Portugal site in Praca do Comercio. Here, there are a vast number of Portuguese wines on offer, with at least 20 available all the time by the glass. Available wines cover Portuguese wine regions, grape varieties, and styles of wine. Port and Sherry are among the offerings. You get a card, put money on it, and go exploring.
We know we only scratched the surface, but a very tasty surface it was. We will be back.