In a large skillet, cook the beef and onion over medium heat until meat is no longer pink; drain. Stir in the sour cream, dill, salt, mustard, curry and pepper; remove from the heat.
Unfold pastry sheets onto a lightly floured surface; cut into 3-in. circles. Place 1-1/2 teaspoons of beef mixture in the center of each circle. Brush edge of pastry with water; fold circles in half.
Place on greased baking sheets. With a fork, press edges to seal and poke holes in top. Bake at 400° for 10-12 minutes or until golden brown. Serve warm with barbecue or sweet-and-sour sauce if desired.