Preheat oven to 400°. Line a rimmed baking sheet with foil.
Arrange asparagus spears on prepared baking sheet, and sprinkle with salt.
Roast until spears are tender when pierced with the tip of a knife, 5 to 7 minutes. Let cool.
Using a serrated bread knife in a gentle sawing motion, trim and discard crusts from bread slices. Cut each bread slice into 3 (3×1-inch) rectangles.
Spread a layer of Dijon-Chive Butter onto all bread pieces. Place salmon slices, folding or ruffling to fit, on 12 buttered bread rectangles. Top with remaining bread rectangles, butter side down.
Using a sharp knife, cut asparagus spears to fit length of sandwiches. Lay an asparagus spear on top of each sandwich. Tie each sandwich with a chive, trimming ends to fit.
Serve immediately, or cover with damp paper towels, place in a covered container, and refrigerate until serving time.
Recipe by TeaTime Magazine at https://teatimemagazine.com/salmon-asparagus-tea-sandwiches/