One of the first interesting things about Cantina da Estrela is the fact that you can decide how much the food and the service are worth and (sorf of) pay the bill based on that. In reality you actually have a lower and a upper limit between which you can choose to pay based on your appreciation. Since all of the restaurant employees come from the Escola de Hotelaria e Turismo de Lisboa (Lisbon’s School of Hospitality), this gives you (and them) a way to continuously evaluate their work. It’s a clever (and attention grabbing) idea that I think should be applied in other restaurants.
(This used to be my High Schoo buildingl, now converted to a boutique hotel!)