The bagel with nova is the gentle end of the appetizing scale, and what defines it is the cure rather than the fish. Nova is salmon that has been cold-smoked rather than aggressively salt-cured, so it is mild, silky, and faintly smoky where true lox is sharp and saline. That softness changes the whole balance of the build: the fish no longer dominates, so the cream cheese, the onion, and the capers move from being a foil for an assertive cure to being equal partners with a delicate one. The sandwich is quieter on purpose, and the quiet is the point.
The craft is the same boiled-then-baked bagel doing structural work, with the toppings recalibrated for a milder fish. A bagel is boiled before it is baked, which sets a tight, chewy crumb and a glossy crust that carries a heavy, slippery load without tearing, and for this build it is properly left untoasted so the crumb keeps its pull against the give of the salmon. The cream cheese is spread thick across both cut faces as the mortar that glues the slippery fish to the bread and gives the accents something to set into. The nova is draped in folds rather than flat slabs so it reads as silk rather than weight. Because the fish is mild, the sharp accents are dialed back: thin red onion and a few capers for brine and bite, tomato for cool acidity, applied with a lighter hand than a salt-cured build would demand, so nothing buries the smoke.
The variations are positions on a graded scale of cured and smoked fish on the same bagel. From here the scale runs up through sable, which is smoked, rich, and oily; smoked sturgeon, which is firm, smoky, and the premium tier; and whitefish salad, which is bound and mayonnaise-dressed rather than sliced. The carrier can also shift to a softer onion bialy. Each of those sits on the same appetizing counter and deserves its own article rather than being crowded in here.