Preheat oven to 350°.
Beat margarine at medium speed with an electric mixer until creamy; gradually add sugar, beating well. Add egg, orange juice, and vanilla.
Combine flour, baking powder, and salt. Add to margarine mixture; stir into a uniform dough.
Shape dough into flat disk. Cover in plastic wrap and refrigerate at least 15 minutes (may be made 2 days ahead).
Roll out chilled dough on a lightly floured surface to 1/8-inch thickness. Cut 3 inch circles with a cookie cutter or drinking glass.
Place 1/2 tsp. of filling in the center of each circle.
Shape into a triangle by folding 2 sides of the cookie circle to the top and pinch together at the sides. Fold remaining side up to the center and pinch together at the sides. Some of the filling should be visible in the center.
Place hamantaschen 1 inch apart on a greased baking sheet.
Bake for 20 - 35 minutes
