*Available by mail order from Kalustyan's (212-685-3451).
Directions
Stir together flour and baking powder. Stir together yogurt, oil, and yolks in another bowl, then gradually add flour, stirring until a soft dough forms. Put dough in a sealed plastic bag and let stand at room temperature 2 hours.
Pulse pistachios, confectioners sugar, and cardamom in a food processor until finely ground (be careful not to overprocess into a paste). Bring water and sugar to a boil in a very small saucepan, stirring, then add syrup to pistachios and pulse to combine.
Preheat oven to 350°F.
Divide dough in half. Keeping one half wrapped in plastic wrap, roll out other half on a well-floured surface into a 15-inch round (about 1/16 inch thick). Cut out as many rounds as possible with a 2 3/4-inch cutter and add scraps to wrapped dough for rerolling. Mound 1 teaspoon filling in center of each round, then moisten edge of round with water and fold over to form a half-moon. Pinch edges together, then crimp with a fork to seal.
Repeat with remaining dough and filling, rerolling scraps.
Bake crescents 1 inch apart on parchment-lined baking sheets in batches in middle of oven until golden, 18 to 20 minutes. Transfer parchment with crescents to a rack and when cookies are just cool enough to handle, toss, a few at a time, in confectioners sugar to coat, knocking off excess. Cool crescents completely on rack.
