Voileivät

An open sandwich, also known as an open-face/open-faced sandwich, bread baser, bread platter or tartine, consists of a slice of bread or toast with one or more food items on top. It has half the number of slices of bread compared to a typical closed sandwich. During the start of the Middle Ages, thin slabs of coarse bread called "trenches" or, in its French derivative, "trenchers", were used as plates. At the end of the meal, the food-soaked trencher was eaten by the diner (from which the expression "trencherman" may come), or perhaps fed to a dog or saved for beggars. Trenchers were as much the harbingers of open-face sandwiches as they were of disposable crockery. A direct precursor to the English sandwich may be found in the Netherlands of the 17th century, where the naturalist John Ray observed that in the taverns, beef hung from the rafters "which they cut into thin slices and eat with bread and butter laying the slices upon the butter". These explanatory specifications reveal the Dutch belegd broodje, open-faced sandwich, was as yet unfamiliar in England.

Source: Wikipedia