The panino con salame mantovano is built around the salame of Mantua, in the low, wet plain of southern Lombardy, and its defining quality is that it leads with garlic and wine. Where many salami keep their seasoning quiet, the Mantuan is forthright: pork minced to a medium-coarse grain, generously dosed with garlic and steeped with the local red wine, then cured soft in the humid Po lowland air so it stays tender rather than hardening to a snap. The taste is pungent and warm, the garlic and the wine carrying through every slice. That assertive, aromatic cure is what makes this a distinct sandwich rather than a generic salame roll, and the panino is built to let it speak.
The craft is in cutting for tenderness and choosing a bread that can stand up to a loud meat. Salame mantovano is sliced moderately thick, because its soft, slightly moist body shreds if shaved too fine and holds its yielding bite when cut with some weight. It wants a plain but sturdy bread, a crusted Lombard roll or a chewy loaf, so the garlic-forward salame meets a carrier with enough structure and neutrality to frame it rather than amplify it. Nothing sharp is added, because the salame already brings its own strong voice and a second pungent element would only compete; the bread is left plain and the slices laid generously. The quality is decided at the Mantuan salumeria where the salame was cut, not at assembly.
The variations are best read against the rest of the salame family, and each is its own subject. The soft jar-preserved salam d'la duja and the cooked, warm salame cotto of Piedmont, the cow-and-goat turgia of the Lanzo valleys, the coarse sweet Varzi of the Oltrepò, the fine hand-tied Felino of Parma, the fennel-cured Sicilian Sant'Angelo. Each is a distinct cure on its own bread, and the garlic-and-wine mantovano stands apart by how forward it is. Each of those deserves its own article rather than being crowded in here.