Very jury-rigged — the pasta (which as you can clearly see is the same kind as used to make Spaghetti-Os) I’d already made and kept to the side, wondering what to do with it. Some random googling turned up this recipe, which was promising.
The trick lay with figuring out how to modify it — I’d no salmon around, but while I could have gone the mayo route as suggested, I didn’t have any and sour cream is just out. So it was a fairly basic version in the end, relying on dill, lemon juice, mustard, salt and pepper to carry it, along with a bit of olive oil. And it actually worked very nicely, filling but flavorful while the beets, raw instead of pickled, added good crunch along with the coolness of the cucumbers.