For breakfast, the bread rolls in the morning - if you get there early, especially somewhere like Pingo Doce, you will find the softest, freshest bread. It's perfect in the morning with a good coffee (don't forget your espresso kettle!). There's also a typical marmalade, made of quince fruit (check it out here) that goes well with it and some soft spread cheese. For lunch, "Bifana" sandwiches are common, which are essentially steak sandwiches made from thinly sliced pork you can usually pick up at the store ('bifanas de porco') and then put in bread rolls; the meat is easy to marinate. Like the other two said, wine and beer (take your pick - I'm a Super Bock fan and beer goes well with these sandwiches). The wine here is great, I'm in the Douro region and you can get a good bottle of wine for about the same price you'd pay for soft drinks. Finally, I'd have to say go to the butcher/fish monger at least a couple of times a month - I like buying mackerel whole (gutted), because I filet them myself - the taste is way different (and much better!) than picking up the pre-packaged / frozen options in my opinion. Hope this helped.