I just returned from Portugal, where I spend 9 fantastic days. Though all of my dining experiences were good, I wanted to recommend a couple of the standouts.
In Lisbon, don't miss O Bica do Sapato. It's situated on the waterfront, and floor-to-ceiling windows, 25-foot ceilings, and a 60s-inspired design make for a spectacular setting. The food matched the decor in every way. I'd describe it as Nouveau Portuguese.
In Porto, we ate at Don Tonho, which is located on the river, just across from Vila Nova da Gaia. They start you off with an assortment of small plates: grilled squid; carrots marinated in olive oil, garlic, and parsely; a salad of tuna and beans; prosciutto, etc. That pretty much eliminated the need for appetizers, as we finished every plate that was presented to us. For a main course, my husband had a spectacular rendition of bacalao, with big hunks of bread substituting for the traditional egg, and the whole thing baked in the oven. I enjoyed my monkfish entree, a local specialty.
Hope this is helpful. If anyone has any dining or lodging questions, I can try to help. We stayed in some fantastic places, too.