This filling arrives at the bread as a finished dish, baked and set before it is ever assembled, and that is the whole reason the sandwich exists. Pounti is an Auvergnat preparation: a savory pork-and-chard terrine, ground pork bound with eggs and milk into a batter, folded through with Swiss chard and herbs and studded with whole prunes, then baked into a loaf you slice. Cut a slab and you get a green-flecked, faintly sweet cross-section with dark prunes set through it. The build is a sturdy crusted loaf, butter optional, and a thick slice of cold pounti laid flat. The region is the Auvergne.
The logic follows from what pounti already is. It is a complete thing before it meets bread: meat for savor, chard for an earthy vegetal note, eggs and milk for a set custardy body, prunes for pockets of dark sweetness against the pork. That means the sandwich does not build a composition so much as carry one, and the bread's job is structural rather than flavoring. The sweet-savory swing is the defining trait and the constraint: the prunes pull the slice toward dessert, the pork and chard pull it back, and a sharp condiment that fights the sweetness breaks the balance the terrine is built on. Butter is barely needed, since the custardy bind already supplies softness and fat. The bread wants a firm crust to hold a slice that is dense but tender, and pounti is best served cool, where it sets cleanly and the prune sweetness stays a counterpoint rather than dominating. Cut too thin it crumbles; cut in an honest slab it holds its green-and-dark cross-section against the crumb.
Variations stay within the Auvergnat idea rather than wandering off it. The same bread takes a pounti with more chard for a greener, lighter slice, a version with raisins in place of prunes for a smaller, more even sweetness, or a thicker cut paired with a leaf of frisée for a bitter edge against the fruit. Each is a small adjustment of the same baked-terrine logic, the bread held constant. The Sandwich au Pounti belongs with the regional dishes folded into bread that the catalog groups under Plat-en-Sandwich, and its specific contribution is a sweet-and-savory baked terrine that arrives at the bread already complete.