No ham in the French repertoire asks for a lighter hand than this one. Jambon de Paris is jambon blanc in its most refined form: a deboned pork leg poached in seasoned stock, pressed into a squared mold, and sliced pale pink. It is mild, faintly bay-and-pepper from the poaching liquid, and tender enough that a thick cut would lose all definition. The components are a fresh baguette, a generous layer of barely-salted butter, and several thin slices of that pale ham. The defining quality here is softness on softness, held together by the one element with backbone: the crust of the bread.
The craft is a matter of proportion and contrast. Because jambon de Paris brings little salt and little chew, the sandwich leans entirely on freshness and on the bread to carry texture. The butter is not a flourish; it is the structural counterweight, spread thick so its cool fat cushions the ham and seals the crumb against the meat's moisture. The ham must be sliced thin and folded into loose ribbons so that air sits between the layers and the bite yields rather than compresses. A short rest after assembly is fine. A long one is not: the soft ham gives its moisture to the soft crumb and the whole thing turns slack, which is why this sandwich is best within a few minutes of being built and rewards a counter that slices to order. The region most associated with it is Paris itself, where the deli counter and the boulangerie sit close enough that the ham and the bread reach the customer on the same clock.
Variations branch off as soon as the ham changes character: dry-cured legs, parsleyed terrines, and cheese-laid versions all take the form somewhere firmer or sharper. Those each earn their own qualifier and their own article rather than crowding in here. Of all the ham sandwiches, this is the one that sits closest to the canonical Jambon-Beurre, because the jambon blanc in the classic build is exactly this pale Paris ham: the baseline against which every more assertive ham is measured.