We stayed in the hugely popular Bairro Alto, which is pretty central. The street we were on was lined with bars and restaurants. The Superbock will find you - it’s everywhere 
A very cute brunch place in that neighborhood is Seventh Brunch, tho it’s not traditional Portuguese food. Taberna Portuguesa was a small, home-style cooking place very popular with locals.
A Cevicheria was recommended to us by @PedroPero , but we didn’t want to spend that much for lunch 
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Here’s my writeup of Prado from our trip two years ago.
