Place a salmon rectangle on a clean work surface. Spoon 1 tablespoon of the cream mixture in a thin lengthwise line, in the center of the salmon. Roll the salmon up, lengthwise, cigar style, to enclose the cream. The two long edges of the salmon rectangle should slightly overlap. Arrange the rolls, seam side up, on a flat plate. Repeat with the remaining salmon rectangles, arranging them in a single layer on the plate. Cover with plastic wrap and refrigerate for at least 2 hours but not more than 24 hours.