Just like a canteen, working as a self service, the meal costs around 8€ for a main dish, dessert and drink. Better to arrive there before 1pm.
A Lisbon’s secret that should not be disclosed, the food is quite simple, décor is absent but definitely is worthwhile if you have the view.
Try to find a seat outside, the terrace as a splendid panorama of the river and the other margin.
Mon-Fr: 08:00-16:00