Mortadella is the great emulsified pork sausage of Bologna — a large, smooth, pale-pink salume of finely ground cured pork bound into a silky paste and studded with glossy cubes of fat, whole peppercorns and, in its prized version, green pistachios. Gently spiced and slow-steamed in vast casings until set, then sliced wafer-thin, it is mild, fatty and faintly sweet-savoury, and it is the direct ancestor of American bologna.