Place cucumber into a strainer and sprinkle with kosher salt; allow cucumber to drain for about 20 minutes.
Transfer cucumber to a piece of cheesecloth and squeeze dry.
Mash cream cheese with seasoned salt and cumin in a bowl. Stir cucumber into cream cheese mixture.
Spread the cucumber mixture on a slice of bread; top with a second slice. Press the slices together lightly and trim off the crusts. Slice each sandwich into 4 triangles by cutting an X shape. Chill sandwiches until serving time.