Preheat oven to 375° F. Line 2 baking sheets with parchment paper.
In a large bowl, beat the butter until smooth. Gradually add the sugar and beat until light and fluffy, 5-10 minutes.
Beat in egg.
Mix in the orange juice, vanilla and salt.
Stir in enough flour to make a soft dough.
Place in a covered and oiled bowl and refrigerate until firm--at least 2 hours.
Divide the dough into two equal pieces. Roll out each piece to about 1/4" thick.
Cut into 3" or 3-1/2" circles with a glass, round cutter or bowl.
Place 1 tsp. filling in center of each circle and fold and crimp into triangles, leaving some filling showing in the center.
Place each hamantaschen on a cookie sheet about 1" apart.
Bake about 13 minutes until golden in color.
