Royal Café is a nice, almost hidden, place to have breakfast, lunch or an afternoon snack. The setting is modern and clean, without being distant. In the back you can find a (rather tiny) terrace.
The main specialties are natural- and organic products. They have a good assortment of salads, sandwiches, fresh juices, various teas and infusions.
It is not cheap, compared to your average Portuguese pastelaria or snackbar, but nothing scandalous, especially if you’re used to Northern European prices.
I like to come here to have lunch or a snack when spending time in Chiado. It is just 100 meters away from the main street in Chiado, but a lot more quiet and less touristic. And it is open on Sunday!!
If it is full try Vertigo.