To create these delightful Pistachio Orange Pastries, follow these straightforward steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Prepare Filling: In a mixing bowl, combine the finely chopped pistachios, orange zest, granulated sugar, orange juice, vanilla extract, ground cinnamon, and salt. Mix well until thoroughly combined.
3. Prepare Phyllo Dough: Carefully unroll the phyllo dough and cut it into rectangles, about 4 inches by 6 inches. Keep the unused sheets covered with a damp cloth to prevent drying out.
4. Assemble Pastries: Place one tablespoon of the filling in the center of a phyllo rectangle. Fold the sides over to encase the filling and then roll it up into a log shape.
5. Egg Wash: Brush the rolled pastry lightly with the beaten egg for a golden color when baked.
6. Place on Baking Sheet: Arrange the filled pastries on the prepared baking sheet, leaving some space between each one.
7. Bake: Bake in the preheated oven for 20-25 minutes, or until golden brown and crispy.
8. Cool: Allow the pastries to cool on the baking sheet for about 10 minutes.
9. Dust with Powdered Sugar: If desired, dust the cooled pastries with powdered sugar before serving.

These simple steps will lead you to create irresistible Pistachio Orange Pastries!