Remove bones and skin from the smoked salmon. Cut in pieces and mix in a food processor. Transfer to a mixing bowl and stir in the mayonnaise.
Run the mixture through a food mill. Mix in the cold liquid aspic jelly, lemon juice, wine and pepper.
Whip the cream until firm. Fold in the salmon mixture. Spoon the mousse into decorative molds.
Refrigerate until mousse is well set and firm. Unmold on serving dish or plate and surround with lettuce leaves.
* If aspic jelly is not available, substitute with 1 tablespoon of unflavored gelatin dissolved in 1/4 cup cold water. Set for 5 minutes. Melt over low heat, and use as directed for aspic jelly.