Smoked salmon and chive holds the salmon constant and lets the herb do the defining work. Cold-smoked salmon is the fixed part across this whole family: thin, oily, salt-and-smoke slices laid over a soft base, here a chive cream cheese on brown bread. What separates this version from its near neighbours is the chive itself. Cut fine and worked through the cheese, it brings a mild green onion note, sharp enough to register but never as assertive as a raw onion, and that gentle allium freshness is precisely the thing the rich, cured salmon wants beside it. The salmon supplies the body and the smoke; the chive is the lift, and naming the sandwich after the herb is naming the part that makes it itself.
The craft is keeping a delicate herb readable against a strong fish. The chive is cut fine and folded evenly through the cream cheese rather than scattered on top, so it is distributed through every bite instead of arriving in clumps, and it is added in a measured amount because too much turns grassy and competes with the smoke instead of cutting it. The cheese does the structural work butter does elsewhere: spread firm and to the edges, it binds the slices, seals the crumb against the oil of the fish, and gives the salmon a stable bed so it does not slide under pressure. The salmon is sliced to translucence so it folds and layers rather than sitting as a heavy slab that drowns the herb. The bread is soft and plain, brown by convention here, because the filling carries all the flavour and a loud crust would only argue with a careful balance.
The variations are the rest of the herbed smoked-salmon shelf, each defined by the green note set against the same cured fish. Smoked salmon and dill trades the onion bite for a feathery, faintly aniseed herb that echoes the cure. Plain cream cheese and smoked salmon drops the herb for capers or nothing at all. The classic brown bread and butter version removes the cheese entirely and lets the salmon stand alone. Each deserves its own article rather than being crowded in here.