for pastry dough

1 1/2 cups all-purpose flour
1 1/4 sticks cold butter; cut into 1/2 inch cubes
1/2 teaspoon salt
3 to 5 tablespoons ice water

for filling

1/4 cup finely diced red onion
2 teaspoons fresh lemon juice
3 1/2 oz sliced fine-quality smoked salmon,; finely chopped (1 1/4 cup
1 tablespoon sour cream at room temperature
1/2 tablespoon unsalted butter, melted
1 teaspoon finely grated fresh lemon zest
1/4 teaspoon black pepper
1 oz salmon roe (caviar)
garnish: fresh dill sprigs

Special equipment: a pastry or bench scraper; 24 (3 1/2-inch)
barquette molds; parchment paper; pie weights or raw rice

Make dough:

Blend together flour, butter, and salt in a bowl with your fingertips
or a pastry blender (or pulse in a food processor) just until most of
mixture resembles coarse meal with small (roughly pea-size) butter
lumps. Drizzle evenly with 3 tablespoons ice water and gently stir
with a fork (or pulse in processor) until incorporated.

Squeeze a small handful: If it doesn't hold together, add remaining
ice water, 1/2 tablespoon at a time, stirring (or pulsing) until just
incorporated, then test again. (Do not overwork mixture, or pastry
will be tough.)

Turn out mixture onto a lightly floured surface and divide into 4
portions. With heel of your hand, smear each portion once or twice in
a forward motion to help distribute fat. Gather dough together with
scraper and divide into 2 pieces, then flatten each piece into a
4-inch square. Chill squares, wrapped in plastic wrap, until firm, at
least 1 hour.

Make barquette shells:

Keeping remaining dough chilled, roll out 1 piece on a lightly floured
surface into a 13-inch square. Arrange 12 barquette molds close
together on a work surface and drape rolled-out dough over molds. Roll
a lightly floured rolling pin over molds to cut dough, then lightly
press into molds. Repeat with remaining dough, then prick each shell
several times with a fork and chill all shells in a shallow baking pan
until firm, about 30
minutes.

Preheat oven to 375°F.

Arrange barquette molds close together in shallow pan and cover with
parchment. Put pie weights on top of parchment (over molds) and bake
in middle of oven until edges of shells are pale golden,about 15
minutes. Carefully remove parchment and weights and bake shells until
golden, 7 to 10 minutes more. Cool shells in molds on a rack 10
minutes, then remove from molds and cool completely.

Prepare filling while shells bake and cool:

Stir together onion, lemon juice, and a pinch of salt in a bowl and
let stand at room temperature 30 minutes. Stir in salmon, sour cream,
butter, zest, and pepper.

Assemble barquettes:

Fill each barquette shell with a scant teaspoon salmon mixture and top
with a scant 1/4 teaspoon caviar.