Heat the oven to 375°F.  Beat the the egg and water in a small bowl with a fork or whisk.

Unfold the pastry sheet on a lightly floured surface.  Roll the pastry sheet into a 13 x 9-inch rectangle.  Brush the pastry with the honey mustard.  Cut the pastry into 8 (about 4 1/2 x 3-inch) rectangles.

Place 1 piece kielbasa in the center of each pastry rectangle. Brush the edges with the egg mixture.  Fold the pastry over the kielbasa and press to seal.  Place the filled pastries seam-side down onto a baking sheet.  Brush the pastries with the egg mixture.

Bake for 25 minutes or until the pastries are golden brown.  Remove the pastries from the baking sheets and let cool on a wire rack for 10 minutes.  Serve with additional honey mustard for dipping.