1 17-1/4 oz. pkg. frozen puff pastry sheets
1 egg yolk, beaten with
2 tbsp. milk
Creme fraiche OR sour cream OR soft cream cheese
Smoked salmon
Chives or finely chopped green scallions

Preheat oven to 400°F. Cut a sheet of the defrosted puff pastry into 3 equal pieces, lengthwise, and put them onto a parchment-lined (or foil-lined) cookie sheet. Brush the surface of the puff pastry with the egg and milk mixture, and bake according to package instructions. Leave to cool. When cool, slice each piece of puff pastry, now risen, in half the long way with a serrated knife. Spread three halves with the creme fraiche (or sour cream or soft, room-temperature cream cheese) and top with smoked salmon and a sprinkling of chives or scallions. Cover with the other half of the "sandwich" and cut each of the three long "sandwiches" into four or five pieces.