Moules frites

Moules-frites or moules et frites is a main dish of mussels and French fries originating in Northern France and Belgium. The title of the dish is French, moules meaning mussels and frites fries, with the Dutch name for the dish meaning the same. It is considered the national dish of Belgium. Although moules-frites are popular in many countries, it is thought that the dish originated in Belgium. It is likely that it was originally created by combining mussels, a popular and cheap foodstuff eaten around the Flemish coast, and fried potatoes, which were commonly eaten around the country in winter when no fish or other food was available.

Source: Wikipedia