Mix all the ingredients except the smoked salmon. Line 4 small ramekins with plastic wrap, leaving the edges hanging over (to make it easier to unmold). Line the bottom and sides with slices of smoked salmon. Pour the avocado preparation evenly into the ramekins. If necessary, cover with smoked salmon. Close the plastic wrap by pressing lightly. Refrigerate for at least one hour. Unmold, decorate the plates, and serve.