Method

1. In a medium bowl, combine the flour, baking powder, and salt.
2. Using a stand mixer fitted with the paddle attachment, combine the lemon and orange zest and juice, vegetable oil, eggs, sugar, and vanilla. Mix on medium speed until combined. Reduce the speed to low, add the flour mixture, mixing until combined and smooth.
3. Transfer the dough to a clean bowl or storage container, cover, and refrigerate for at least 4 hours or up to overnight until firm. If making 12 to 14 cookies, divide the dough in half. Wrap half of the dough or store in an airtight plastic bag and freeze for up to 3 months
4. Position the oven racks in the upper and lower third of the oven and preheat to 350˚F. Line two baking sheets with parchment paper.
5. Lightly flour the work surface. Cut the dough in half. Working with one piece at a time, roll out until the dough is ¼-inch thick. Using a 3 ½-inch round cookie cutter, cut into circles and set on the prepared baking sheets, leaving about an inch between. Any remaining dough can be pushed back together and re-rolled.
6. Using a pastry bag fitted with a round tip or a spoon, place a small amount of filling in the center of each circle. Dip your fingertip in water and lightly moisten the outside rim of each circle. Gently fold the 3 edges of the circle to form a triangle around the filling, then pinch the corners to close.
7. Bake, rotating the pans once midway through baking, until a light golden brown, 12 to 15 minutes. Transfer to a cooling rack and let cool completely before serving.