Lay salmon on plastic wrap in a 12 x 8" rectangle. Mix cream cheese with dill and spread carefully over the salmon. Along the long edge, about 1" in, line the capers in a row. Starting at the capers end slowly roll up, like a jelly roll, using the plastic wrap to help you. Squeeze gently to form a cylinder and twist ends closed. Freeze for at least 4 hours. Keeps well in the freezer for one month. Take from the freezer 20 min. before serving and let stand at room temperature. Slice and arrange on cucumber slices. Garnish with red onion and dill sprigs. Let stand 10 min. and then serve.