Surveys of French sandwich sales have repeatedly found it's the best-selling sandwich in the country, outselling every hot or elaborate rival by sheer volume.
A jambon-beurre is nothing more than a fresh baguette split open, spread generously with salted butter, and layered with a few slices of good ham — no lettuce, no mustard, no extras. Bakeries and sandwich counters across Paris sell thousands a day to office workers eating standing up or on a bench.