Place 4 slices of smoked salmon side by side on a cutting board, forming a rectangle.
Spread cream cheese evenly on salmon, about 1/8 inch thick.
Cut sweet bread to same size as salmon; place on top of smoked salmon and cream cheese.
Roll up lengthwise to create a roulade, wrap tightly with plastic wrap and place in freezer for 2 hrs.
In the meantime, mix sour cream with chives, lemon juice, salt and pepper to taste.
Remove roulade from freezer, slice in 1/4 inch slices.
Place a dollop of the sour cream mixture on top of roulade slices. Serve along with lettuce, red onions, capers and lemon wedge.