In a mixing bowl, combine the cream fraiche, cream cheese, dill, chives, and lemon zest. Mix well. Season with salt and pepper.

Place the slice of salmon on a piece of plastic wrap, with the small end closes to you, on a flat surface. Season the slices of salmon with the pepper. Spread some of the cheese mixture evenly over each slice of salmon. Trim ends to make even. Then, beginning at the bottom, roll up the salmon, jelly roll style, securely, pressing to close. Wrap each salmon roll in plastic wrap. Refrigerate until ready to use.

About 30 minutes before serving, place the salmon rolls in the freezer; this will make slicing easy.

To serve, using a chef's knife, slice the salmon into 1/2-inch slices. Remove the plastic wrap and discard. Place the salmon on the toasted melba. Using a pear-handle spoon, place some caviar on top of the salmon. Garnish with a sprig of dill and sour cream.