Prego no Pão is a popular Portuguese sandwich that consists of thinly sliced beef steak marinated in garlic and spices, served on a crusty roll. The sandwich is typically topped with mustard or hot sauce and can be customized with additional ingredients such as cheese, fried egg, or sautéed onions. Prego no Pão is a delicious and satisfying option for a quick and tasty meal in Lisbon.