Smoked salmon pairs perfectly with puff pastry, creating a savory tart that will wow the guests at your next brunch or cocktail party. Blind baking the pastry ensures a super-crisp crust (no soggy centers here). Top it off with a tangy, herbed cream cheese filling, crisp cucumbers and smoky salmon—all of which can be prepped in advance for quick assembly.
Preheat the oven to 425 degrees F with a rack in the center. Line a baking sheet with parchment.
Lightly flour a work surface and gently unfold the puff pastry dough. Using a rolling pin, roll out the dough into a 10-by-12-inch rectangle. Score a 1-inch border along all four sides with a sharp knife then prick the area inside the border all over with a fork. This allows steam to release and a rim to rise around the tart.
Transfer the puff pastry to the prepared baking sheet and bake, rotating the pan halfway through, until golden brown and puffy, about 18 minutes total. Remove the pastry from the baking sheet and allow it to cool on a cutting board or wire rack for 10 minutes. (see Cook's Note)
While the pastry is baking, whip the cream cheese, yogurt, lemon juice, 1/4 teaspoon salt and several grinds of black pepper in a large bowl with an electric mixer until light and fluffy, about 2 minutes. Fold in the capers, lemon zest, 2 tablespoons chopped dill and 2 tablespoons chopped chives and set aside.
Just before serving, evenly spread the cream cheese filling over the baked pastry with an offset spatula, leaving the 1-inch border exposed. Arrange the smoked salmon and cucumber on top and sprinkle the tart with the dill fronds, remaining 1 tablespoon chives and some black pepper.
The puff pastry can be baked up to 1 day in advance. Store in an airtight container to keep it crisp.