Blend jam and cream cheese; set aside. Slice cucumbers lengthwise into thin, long strips using a vegetable peeler or a mandolin. Lay the slices on a flexible cutting mat or parchment paper, overlapping slightly, to create a large square. Gently spread the cream cheese mixture over the cucumbers. Layer slices of turkey over the top. Add the carrots and onion in a narrow line down the left side. Left up the edge of the cutting mat to fold the roll onto itself; roll tightly. Insert a toothpick into the center of each cucumber strip, then slice the roll with a paring knife between each cucumber slice.