Persian Sweet Pastry

Combine 1 cup of sour cream, 2 teaspoons of sugar, and yeast in a bowl. Allow the mixture to rest for 5 minutes. Combine egg, vinegar, and oil in a separate bowl and mix with the sour cream mixture until well incorporated.

Combine 3 cups of flour in a large bowl and incorporate 1/2 cup of butter until the mixture resembles coarse crumbs. Gradually add the sour cream mixture to the flour mixture, stirring until a dough forms.

Transfer the dough onto a lightly floured surface and knead for 10 minutes, until it reaches a smooth yet slightly sticky consistency. Divide the dough into 4 equal pieces and wrap each piece in plastic wrap. Refrigerate for at least 2 hours or overnight, until firm.

Preheat the oven to 350 degrees F (175 degrees C). Combine melted butter, 2 1/2 cups of sugar, and vanilla extract in a large bowl. Stir in 4 cups of flour to create the filling mixture. Beat in egg whites until well combined.

Roll out one piece of dough into an 8x12-inch rectangle on a lightly floured surface. Sprinkle 1/4 of the filling mixture over the dough, leaving a 1/2-inch border on the long sides. Cover with plastic wrap and flatten with a rolling pin. Roll the dough into a tight cylinder, starting with one of the long sides.

Cut the roll into 2-inch pieces at a slight angle. Arrange the pieces on a rimmed baking sheet and gently press down the tops to flatten slightly. Repeat with the remaining 3 pieces of dough and filling.

Whisk together egg yolks and yogurt to create a glaze. Brush the glaze over the pieces of dough.

Bake in the preheated oven for 20 to 30 minutes, or until golden brown. Allow the pastries to cool for 15 minutes before serving.