Trendy, Norwegian-run Ground Burger is an obvious standout in Lisbon's ongoing gourmet-burger war, sticking to perfectly executed American-style classics (cheese, bacon-cheese and chilli-cheese burgers) and great hand-cut chips and onion rings. The local and international craft-beer list is probably Lisbon's most impressive for such a restaurant. It's tucked away almost discreetly around the side of an office building near Museu Calouste Gulbenkian.
There's a second outlet in Mercado da Ribeira.