Pay what you eat! "Kilo" or "quilo" restaurants in Brazil

The restaurants selling food from a diverse buffet from salads, beans, grilled meat, fish and desserts are very popular in Brazil.
After serving by yourself your food, they will put your dish and you will pay according to the final weight. The weight of the dish itself is discounted.
Usually, they advertise the price by: "R$ 3,00 for 100 gramas" or "R$ 30,00 per 01 kilo"

It can be from a simple food or some a little more sophisticated.