SMOKED SALMON TART

Steps:

• MAKE THE PASTRY: Put flour, baking powder and 1/2 teaspoon salt in the bowl of a food processor. Pulse briefly, then add butter all at once and whir until mixture resembles wet sand. Add egg and continue just until dough comes together. (Alternatively, cut butter into dry ingredients in a mixing bowl and mix by hand.) Knead dough lightly on counter-top, then divide into four pieces and form each into a ball. Wrap with plastic film and flatten to 1-inch-thick disks. Refrigerate for at least 1 hour. MAKE THE HORSERADISH CREAM: Mix together crème fraîche, horseradish, mustard and lemon zest. Season generously with salt and pepper, then keep cool. (If cream firms upon standing, beat with a fork.) Heat oven to 400 degrees. Put onion in a small bowl and season with salt and pepper. Add olive oil and mix to coat. Roll out each piece of dough to an 8-inch-diameter circle. Place the pastry disks on parchment-lined baking sheets. Sprinkle onion slices over each round. Bake tart rounds for 6 to 7 minutes, until pastry is lightly browned and puffed, and onions are starting to brown. (Turn pans halfway through for even browning.) Let cool for a minute or two. ASSEMBLE THE TART: Put pastry on a cutting board. Cut into 6 or 8 wedges. Spoon some horseradish cream onto each wedge. Tear salmon slices into wide ribbons and lay them over the cream. (Use 1 ounce salmon per tart.) Top each wedge with a tiny spoonful of roe, if using, and sprinkle with chives and tarragon. Serve directly from the board.